1.
Sedimentary
–
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earths surface and within bodies of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place. The particles that form a rock by accumulating are called sediment. Sedimentation may also occur as minerals precipitate from solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earths crust is extensive, sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding, sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of rock strata is the main source for an understanding of the Earths history, including palaeogeography, paleoclimatology. The scientific discipline that studies the properties and origin of rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geomorphology, geochemistry, sedimentary rocks have also been found on Mars. Clastic sedimentary rocks are composed of rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, feldspar, rock fragments, clay minerals, and mica, any type of mineral may be present, clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions, gravel, sand, and mud and this tripartite subdivision is mirrored by the broad categories of rudites, arenites, and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape, conglomerates and breccias), composition. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel, composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks, all other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Clean sandstones with open space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes, six sandstone names are possible using the descriptors for grain composition and the amount of matrix. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles and these relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension
Sedimentary
–
Middle
Triassic marginal marine sequence of siltstones (reddish layers at the cliff base) and limestones (brown rocks above),
Virgin Formation, southwestern
Utah, USA
Sedimentary
–
Sedimentary rocks on Mars, investigated by NASA's
Curiosity Mars rover
Sedimentary
–
Steeply dipping sedimentary rock strata along the
Chalous Road in northern
Iran
Sedimentary
–
Claystone deposited in
Glacial Lake Missoula,
Montana,
United States. Note the very fine and flat bedding, common for distal
lacustrine deposition.
2.
Clay minerals
–
Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life and they are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Clays form flat hexagonal sheets similar to the micas, Clay minerals are common weathering products and low-temperature hydrothermal alteration products. Clay minerals are common in soils, in fine-grained sedimentary rocks such as shale, mudstone. Clay minerals are usually ultrafine-grained and so may require special techniques for their identification. These methods can be augmented by polarized light microscopy, a traditional technique establishing fundamental occurrences or petrologic relationships. Given the requirement of water, clay minerals are rare in the Solar System, though they occur extensively on Earth where water has interacted with other minerals. Clay minerals have been detected at several locations on Mars including Echus Chasma and Mawrth Vallis and the Memnonia quadrangle, spectrography has confirmed their presence on asteroids including the dwarf planet Ceres and Tempel 1 as well as Jupiters moon Europa. A1,1 clay would consist of one sheet and one octahedral sheet. A2,1 clay consists of an octahedral sheet sandwiched between two sheets, and examples are talc, vermiculite and montmorillonite. Smectite group which includes dioctahedral smectites such as montmorillonite, nontronite and beidellite, in 2013, analytical tests by the Curiosity rover found results consistent with the presence of smectite clay minerals on the planet Mars. Illite group which includes the clay-micas, illite is the only common mineral. Chlorite group includes a variety of similar minerals with considerable chemical variation. Other 2,1 clay types exist such as sepiolite or attapulgite, mixed layer clay variations exist for most of the above groups. Ordering is described as random or regular ordering, and is described by the term reichweite. Literature articles will refer to a R1 ordered illite-smectite, for example and this type would be ordered in an ISISIS fashion. R0 on the other hand describes random ordering, and other advanced ordering types are also found, mixed layer clay minerals which are perfect R1 types often get their own names. R1 ordered chlorite-smectite is known as corrensite, R1 illite-smectite is rectorite, knowledge of the nature of clay became better understood in the 1930s with advancements in x-ray diffraction technology necessary to analyze the molecular nature of clay particles
Clay minerals
–
Oxford Clay (
Jurassic) exposed near
Weymouth, England.
3.
Quartz
–
Quartz is the second most abundant mineral in Earths continental crust, behind feldspar. There are many different varieties of quartz, several of which are semi-precious gemstones, since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. The word quartz is derived from the German word Quarz and its Middle High German ancestor twarc, the Ancient Greeks referred to quartz as κρύσταλλος derived from the Ancient Greek κρύος meaning icy cold, because some philosophers apparently believed the mineral to be a form of supercooled ice. Today, the rock crystal is sometimes used as an alternative name for the purest form of quartz. Quartz belongs to the crystal system. The ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end, well-formed crystals typically form in a bed that has unconstrained growth into a void, usually the crystals are attached at the other end to a matrix and only one termination pyramid is present. However, doubly terminated crystals do occur where they develop freely without attachment, a quartz geode is such a situation where the void is approximately spherical in shape, lined with a bed of crystals pointing inward. α-quartz crystallizes in the crystal system, space group P3121 and P3221 respectively. β-quartz belongs to the system, space group P6222 and P6422. These space groups are truly chiral, both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks. The transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, although many of the varietal names historically arose from the color of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Color is an identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others. The most important distinction between types of quartz is that of macrocrystalline and the microcrystalline or cryptocrystalline varieties, the cryptocrystalline varieties are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline. Chalcedony is a form of silica consisting of fine intergrowths of both quartz, and its monoclinic polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are agate, carnelian or sard, onyx, heliotrope, amethyst is a form of quartz that ranges from a bright to dark or dull purple color. The worlds largest deposits of amethysts can be found in Brazil, Mexico, Uruguay, Russia, France, Namibia, sometimes amethyst and citrine are found growing in the same crystal. It is then referred to as ametrine, an amethyst is formed when there is iron in the area where it was formed
Quartz
–
Quartz
crystal cluster from
Tibet
Quartz
–
Clear rock crystals on a white base
Quartz
–
Amethyst crystals on matrix
Quartz
–
Citrine from Brazil
4.
Clastic
–
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport whether in suspension or as bed load, clastic sedimentary rocks are rocks composed predominantly of broken pieces or clasts of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on size, clast and cementing material composition. The classification factors are often useful in determining a samples environment of deposition, an example clastic environment would be a river system in which the full range of grains being transported by the moving water consist of pieces eroded from solid rock upstream. Grain size varies from clay in shales and claystones, through silt in siltstones, sand in sandstones, the Krumbein phi scale numerically orders these terms in a logarithmic size scale. Siliciclastic rocks are clastic rocks that are composed almost exclusively of silicon. The composition of sedimentary rocks includes the chemical and mineralogical components of the framework as well as the cementing material that make up these rocks. Boggs divides them into four categories, major minerals, accessory minerals, rock fragments, major minerals can be categorized into subdivisions based on their resistance to chemical decomposition. Those that possess a great resistance to decomposition are categorized as stable, while those that do not are considered less stable, the most common stable mineral in siliciclastic sedimentary rocks is quartz. Quartz makes up approximately 65 percent of framework grains present in sandstones, less stable minerals present in this type of rocks are feldspars, including both potassium and plagioclase feldspars. Feldspars comprise a considerably lesser portion of framework grains and minerals and they only make up about 15 percent of framework grains in sandstones and 5% of minerals in shales. Clay mineral groups are present in mudrocks but can be found in other siliciclastic sedimentary rocks at considerably lower levels. Accessory minerals are associated with those whose presence in the rock are not directly important to the classification of the specimen and these generally occur in smaller amounts in comparison to the quartz, and feldspars. Furthermore, those that do occur are generally heavy minerals or coarse grained micas, rock fragments also occur in the composition of siliciclastic sedimentary rocks and are responsible for about 10 -15 percent of the composition of sandstone. They generally make up most of the gravel size particles in conglomerates, though they sometimes are, rock fragments are not always sedimentary in origin. They can also be metamorphic or igneous, chemical cements vary in abundance but are predominantly found in sandstones. The two major types, are based and carbonate based
Clastic
–
A
thin section of a clast (sand grain), derived from a
basalt scoria.
Vesicles (air bubbles) can be seen throughout the clast. Plane light above, cross-
polarized light below. Scale box is 0.25 mm
Clastic
–
Claystone from
Montana
Clastic
–
Conglomerate
Clastic
–
Breccia. Notice the angular nature of the large clasts
5.
Sedimentary rock
–
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earths surface and within bodies of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place. The particles that form a rock by accumulating are called sediment. Sedimentation may also occur as minerals precipitate from solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earths crust is extensive, sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding, sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of rock strata is the main source for an understanding of the Earths history, including palaeogeography, paleoclimatology. The scientific discipline that studies the properties and origin of rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geomorphology, geochemistry, sedimentary rocks have also been found on Mars. Clastic sedimentary rocks are composed of rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, feldspar, rock fragments, clay minerals, and mica, any type of mineral may be present, clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions, gravel, sand, and mud and this tripartite subdivision is mirrored by the broad categories of rudites, arenites, and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape, conglomerates and breccias), composition. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel, composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks, all other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Clean sandstones with open space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes, six sandstone names are possible using the descriptors for grain composition and the amount of matrix. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles and these relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension
Sedimentary rock
–
Middle
Triassic marginal marine sequence of siltstones (reddish layers at the cliff base) and limestones (brown rocks above),
Virgin Formation, southwestern
Utah, USA
Sedimentary rock
–
Sedimentary rocks on Mars, investigated by NASA's
Curiosity Mars rover
Sedimentary rock
–
Steeply dipping sedimentary rock strata along the
Chalous Road in northern
Iran
Sedimentary rock
–
Claystone deposited in
Glacial Lake Missoula,
Montana,
United States. Note the very fine and flat bedding, common for distal
lacustrine deposition.
6.
Mud
–
A MUD, is a multiplayer real-time virtual world, usually text-based. MUDs combine elements of role-playing games, hack and slash, player versus player, interactive fiction, players can read or view descriptions of rooms, objects, other players, non-player characters, and actions performed in the virtual world. Players typically interact with other and the world by typing commands that resemble a natural language. Traditional MUDs implement a video game set in a fantasy world populated by fictional races and monsters. The objective of this sort of game is to slay monsters, explore a world, complete quests, go on adventures, create a story by roleplaying. Many MUDs were fashioned around the rules of the Dungeons & Dragons series of games. MUDs have attracted the interest of scholars from many fields, including communications, sociology, law. At one time, there was interest from the United States military in using them for teleconferencing, most MUDs are run as hobbies and are free to players, some may accept donations or allow players to purchase virtual items, while others charge a monthly subscription fee. MUDs can be accessed via standard telnet clients, or specialized MUD clients which are designed to improve the user experience, numerous games are listed at various web portals, such as The Mud Connector. Indeed, before the invention of the term MMORPG, games of this style were simply called graphical MUDs, a number of influential MMORPG designers began as MUD developers and/or players or were involved with early MUDs. Colossal Cave Adventure, created in 1975 by Will Crowther on a DEC PDP-10 computer, was the first widely used adventure game, the game was significantly expanded in 1976 by Don Woods. Also called Adventure, it contained many D&D features and references, numerous graphical MUDs were created on the PLATO system at the University of Illinois and other American universities that used PLATO, beginning in 1975. Among them were pedit5, oubliette, moria, avathar, krozair, dungeon, dnd, crypt, PLATO MUDs are often ignored by historians and by the creators of other MUDs whose work came later. Inspired by Adventure, a group of students at MIT in the summer of 1977 wrote a game for the PDP-10 minicomputer, called Zork, Zork was ported, under the filename DUNGEN, to FORTRAN by a programmer working at DEC in 1978. In 1978 Roy Trubshaw, a student at Essex University in the UK and he named the game MUD, in tribute to the Dungeon variant of Zork, which Trubshaw had greatly enjoyed playing. Trubshaw converted MUD to BCPL, before handing over development to Richard Bartle, the game revolved around gaining points till one achieved the Wizard rank, giving the character immortality and special powers over mortals. It became the first Internet multiplayer online role-playing game in 1980, the original MUD game was closed down in late 1987, reportedly under pressure from CompuServe, to whom Richard Bartle had licensed the game. This left MIST, a derivative of MUD1 with similar gameplay, as the only remaining MUD running on the Essex University network, MIST ran until the machine that hosted it, a PDP-10, was superseded in early 1991
Mud
–
A combat in
The Shadow of Yserbius, an early graphical MUD
Mud
7.
Clay mineral
–
Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life and they are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Clays form flat hexagonal sheets similar to the micas, Clay minerals are common weathering products and low-temperature hydrothermal alteration products. Clay minerals are common in soils, in fine-grained sedimentary rocks such as shale, mudstone. Clay minerals are usually ultrafine-grained and so may require special techniques for their identification. These methods can be augmented by polarized light microscopy, a traditional technique establishing fundamental occurrences or petrologic relationships. Given the requirement of water, clay minerals are rare in the Solar System, though they occur extensively on Earth where water has interacted with other minerals. Clay minerals have been detected at several locations on Mars including Echus Chasma and Mawrth Vallis and the Memnonia quadrangle, spectrography has confirmed their presence on asteroids including the dwarf planet Ceres and Tempel 1 as well as Jupiters moon Europa. A1,1 clay would consist of one sheet and one octahedral sheet. A2,1 clay consists of an octahedral sheet sandwiched between two sheets, and examples are talc, vermiculite and montmorillonite. Smectite group which includes dioctahedral smectites such as montmorillonite, nontronite and beidellite, in 2013, analytical tests by the Curiosity rover found results consistent with the presence of smectite clay minerals on the planet Mars. Illite group which includes the clay-micas, illite is the only common mineral. Chlorite group includes a variety of similar minerals with considerable chemical variation. Other 2,1 clay types exist such as sepiolite or attapulgite, mixed layer clay variations exist for most of the above groups. Ordering is described as random or regular ordering, and is described by the term reichweite. Literature articles will refer to a R1 ordered illite-smectite, for example and this type would be ordered in an ISISIS fashion. R0 on the other hand describes random ordering, and other advanced ordering types are also found, mixed layer clay minerals which are perfect R1 types often get their own names. R1 ordered chlorite-smectite is known as corrensite, R1 illite-smectite is rectorite, knowledge of the nature of clay became better understood in the 1930s with advancements in x-ray diffraction technology necessary to analyze the molecular nature of clay particles
Clay mineral
–
Gay Head cliffs in
Martha's Vineyard consist almost entirely of clay.
Clay mineral
–
Electron microscope photograph of smectite clay – magnification 23,500
Clay mineral
–
Quaternary clay in
Estonia
Clay mineral
–
Deforestation for clay extraction in
Rio de Janeiro,
Brazil. The picture is of Morro da Covanca, Jacarepaguá.
8.
Silt
–
Silt is granular material of a size between sand and clay, whose mineral origin is quartz and feldspar. Silt may occur as a soil or as sediment mixed in suspension with water in a body of such as a river. It may also exist as soil deposited at the bottom of a water body, Silt has a moderate specific area with a typically non-sticky, plastic feel. Silt usually has a floury feel when dry, and a slippery feel when wet, Silt can be visually observed with a hand lens. Silt is created by a variety of physical processes capable of splitting the generally sand-sized quartz crystals of primary rocks by exploiting deficiencies in their lattice and these involve chemical weathering of rock and regolith, and a number of physical weathering processes such as frost shattering and haloclasty. The main process is abrasion through transport, including fluvial comminution, aeolian attrition and it is in semi-arid environments that substantial quantities of silt are produced. Silt is sometimes known as rock flour or stone dust, especially produced by glacial action. Mineralogically, silt is composed mainly of quartz and feldspar, sedimentary rock composed mainly of silt is known as siltstone. Liquefaction created by an earthquake is silt suspended in water that is hydrodynamically forced up from below ground level. In the Udden–Wentworth scale, silt particles range between 0.0039 and 0.0625 mm, larger than clay but smaller than sand particles, ISO14688 grades silts between 0.002 mm and 0.063 mm. In actuality, silt is chemically distinct from clay, and unlike clay, grains of silt are approximately the size in all dimensions, furthermore. Clays are formed from thin plate-shaped particles held together by electrostatic forces, according to the U. S. Department of Agriculture Soil Texture Classification system, the sand-silt distinction is made at the 0.05 mm particle size. The USDA system has been adopted by the Food and Agriculture Organization, in the Unified Soil Classification System and the AASHTO Soil Classification system, the sand-silt distinction is made at the 0.075 mm particle size. Silts and clays are distinguished mechanically by their plasticity, Silt is easily transported in water or other liquid and is fine enough to be carried long distances by air in the form of dust. Thick deposits of silty material resulting from deposition by aeolian processes are called loess. Silt and clay contribute to turbidity in water, Silt is transported by streams or by water currents in the ocean. When silt appears as a pollutant in water the phenomenon is known as siltation, Silt, deposited by annual floods along the Nile River, created the rich, fertile soil that sustained the Ancient Egyptian civilization. In south east Bangladesh, in the Noakhali district, cross dams were built in the 1960s whereby silt gradually started forming new land called chars, the district of Noakhali has gained more than 28 square miles of land in the past 50 years
Silt
–
A silted lake located in
Eichhorst,
Germany
9.
Calcite
–
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. The Mohs scale of hardness, based on scratch hardness comparison. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite, aragonite will change to calcite at 380–470 °C, and vaterite is even less stable. Calcite is derived from the German Calcit, a term coined in the 19th century from the Latin word for lime and it is thus etymologically related to chalk. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals, however, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms and it may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form and its fracture is conchoidal, but difficult to obtain. It has a defining Mohs hardness of 3, a gravity of 2.71. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. A transparent variety called Iceland spar is used for optical purposes, acute scalenohedral crystals are sometimes referred to as dogtooth spar while the rhombohedral form is sometimes referred to as nailhead spar. Single calcite crystals display an optical property called birefringence and this strong birefringence causes objects viewed through a clear piece of calcite to appear doubled. The birefringent effect was first described by the Danish scientist Rasmus Bartholin in 1669, at a wavelength of ~590 nm calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively. Between 190 and 1700 nm, the refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite, like most carbonates, will dissolve with most forms of acid, calcite can be either dissolved by groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, and dissolved ion concentrations. Although calcite is fairly insoluble in water, acidity can cause dissolution of calcite. Ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite, calcite exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases. When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures. On a landscape scale, continued dissolution of calcium carbonate-rich rocks can lead to the expansion and eventual collapse of cave systems, high-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry
Calcite
–
A one-inch calcite
rhomb that shows the
double image refraction property
Calcite
–
Crystal structure of calcite
Calcite
–
faceted calcite, oval cut, 1.12ct, Mexico.
Calcite
–
Doubly terminated calcite crystal.
10.
Fissility (geology)
–
Fissility or fissibility refers to the property of rocks to split along planes of weakness into thin sheets. This is commonly observed in shales, which are sedimentary rocks, and in slates and phyllites, the fissility in these rocks is caused by the preferred alignment of platy phyllosilicate grains due to compaction, deformation or new mineral growth. A highly fissile rock splits easily along the cleavage
Fissility (geology)
–
Phyllite showing cleavage
11.
Mudstone
–
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope, with increased pressure over time, the platey clay minerals may become aligned, with the appearance of fissility or parallel layering. This finely bedded material that splits readily into thin layers is called shale, the lack of fissility or layering in mudstone may be due to either original texture or the disruption of layering by burrowing organisms in the sediment prior to lithification. Mud rocks such as mudstone and shale comprise some 65% of all sedimentary rocks, mudstone looks like hardened clay and, depending upon the circumstances under which it was formed, it may show cracks or fissures, like a sun-baked clay deposit. Mudstone can be separated into categories, Siltstone – more than half of the composition is silt-sized particles. Claystone – more than half of the composition is clay-sized particles, mudstone – hardened mud, a mix of silt and clay sized particles. Mudstone can include, Shale – exhibits lamination or fissility, argillite – has undergone low-grade metamorphism. In the Dunham classification of limestones, a mudstone is a carbonate rock that contains less than 10% allochems in a carbonate mud matrix. As defined by the Dunham classification, a mudstone is more or less synonymous with calcilutite, on December 13,2016, NASA reported further evidence supporting habitability on the planet Mars as the Curiosity rover climbed higher, studying younger layers, on Mount Sharp. Also reported, the soluble element boron was detected for the first time on Mars. Since landing on Mars in August 2012, Curiosity has driven 15.0 km, mudstone on planet Mars Aeolis quadrangle Composition of Mars Timeline of Mars Science Laboratory Tonstein
Mudstone
–
Mudstone formation on
Lyme Regis East Beach.
Mudstone
–
Sample of Mudstone
12.
Slate
–
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock, foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression. The foliation in slate is called slaty cleavage and it is caused by strong compression causing fine grained clay flakes to regrow in planes perpendicular to the compression. Slate is frequently grey in color, especially when seen, en masse, Slate is not to be confused with shale, from which it may be formed, or schist. The word slate is used for certain types of object made from slate rock. It may mean a single roofing tile made of slate, or a writing slate and this was traditionally a small smooth piece of the rock, often framed in wood, used with chalk as a notepad or noticeboard, and especially for recording charges in pubs and inns. The phrases clean slate and blank slate come from this usage, before the mid-19th century, the terms slate, shale and schist were not sharply distinguished. In the context of underground mining in the United States. For example, roof slate referred to shale above a coal seam, occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids, Slate can be made into roofing slates, a type of roof shingle, or more specifically a type of roof tile, which are installed by a slater. Slate has two lines of breakability – cleavage and grain – which make it possible to split the stone into thin sheets, when broken, slate retains a natural appearance while remaining relatively flat and easy to stack. Slate is particularly suitable as a material as it has an extremely low water absorption index of less than 0. 4%. In fact, this natural slate, which requires only minimal processing, has the lowest embodied energy of all roofing materials, natural slate is used by building professionals as a result of its beauty and durability. Slate is incredibly durable and can last several hundred years, often little or no maintenance. Its low water makes it very resistant to frost damage and breakage due to freezing. Natural slate is also fire resistant and energy efficient, Slate roof tiles are usually fixed either with nails, or with hooks as is common with Spanish slate. In the UK, fixing is typically with double nails onto timber battens or nailed directly onto timber sarking boards, nails were traditionally of copper, although there are modern alloy and stainless steel alternatives. Both these methods, if used properly, provide a long-lasting weathertight roof with a lifespan of around 80–100 years, Slate roofs are still used today
Slate
–
Slate
Slate
–
Slate Macro (~ 6 cm long and ~ 4 cm high)
Slate
–
Slate roof
Slate
–
Mules carrying slate roof tiles.
Dharamsala, India. 1993
13.
Schist
–
Schist is a medium-grade metamorphic rock with medium to large, flat, sheet-like grains in a preferred orientation. It is defined by having more than 50% platy and elongated minerals, often finely interleaved with quartz and these lamellar minerals include micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a form called quartz schist is produced. Schist forms at a temperature and has larger grains than phyllite. Geological foliation with medium to large grained flakes in a preferred orientation is called schistosity. The names of various schists are derived from their mineral constituents, for example, schists rich in mica are called mica schists and include biotite or muscovite. Most schists are mica schists, but graphite and chlorite schists are also common, Schists are also named for their prominent or perhaps unusual mineral constituents, as in the case of garnet schist, tourmaline schist, and glaucophane schist. The individual mineral grains in schist, drawn out into flaky scales by heat and pressure, Schist is characteristically foliated, meaning that the individual mineral grains split off easily into flakes or slabs. Most schists are derived from clays and muds that have passed through a series of processes involving the production of shales, slates and phyllites as intermediate steps. Certain schists are derived from fine-grained igneous rocks such as basalts, before the mid-18th century, the terms slate, shale and schist were not sharply differentiated by those involved with mining. In the context of underground mining, shale was frequently referred to as slate well into the 20th century. During metamorphism, rocks which were originally sedimentary, igneous or metamorphic are converted into schists, if the composition of the rocks was originally similar, they may be very difficult to distinguish from one another if the metamorphism has been great. A quartz-porphyry, for example, and a fine grained feldspathic sandstone, usually, however, it is possible to distinguish between sedimentary and igneous schists and gneisses. If, for example, the district occupied by these rocks has traces of bedding, clastic structure, or unconformability. In other cases intrusive junctions, chilled edges, contact alteration or porphyritic structure may prove that in its original condition a metamorphic gneiss was an igneous rock. Such rocks as limestones, dolomites, quartzites and aluminous shales have very definite chemical characteristics which distinguish them even when completely recrystallized, the schists are classified principally according to the minerals they consist of and on their chemical composition. For example, many metamorphic limestones, marbles, and calc-schists, with crystalline dolomites, contain silicate minerals such as mica, tremolite, diopside, scapolite, quartz and they are derived from calcareous sediments of different degrees of purity. Another group is rich in quartz, with amounts of white and black mica, garnet, feldspar, zoisite
Schist
–
Schist specimen showing the characteristic "scaly" schistose texture, caused by platy micas
Schist
–
Microscopic view of garnet-mica-schist in
thin section under polarized light with a large garnet crystal (black) in a matrix of quartz and feldspar (white and gray grains) and parallel strands of mica (red, purple and brown).
Schist
–
View of cut garnet-mica-schist
Schist
–
Manhattan schist from southeastern New York State
14.
Coal mining
–
Coal mining is the process of extracting coal from the ground. Coal is valued for its content, and, since the 1880s, has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore, in the United Kingdom and South Africa a coal mine and its structures are a colliery, a coal mine a pit, the above-ground structures the pit head. In Australia, colliery generally refers to a coal mine. In the United States colliery has been used to describe a coal mine operation, Coal mining has had many developments over the recent years, from the early days of men tunnelling, digging and manually extracting the coal on carts, to large open cut and long wall mines. Mining at this scale requires the use of draglines, trucks, conveyors, hydraulic jacks, small-scale mining of surface deposits dates back thousands of years. For example, in Roman Britain, the Romans were exploiting most of the major coalfields by the late 2nd century AD. The Industrial Revolution, which began in Britain in the 18th century and later spread to continental Europe, international trade expanded rapidly when coal-fed steam engines were built for the railways and steamships. Until the late nineteenth century coal was mined using a pick and shovel. Coal-cutting machines were introduced in the 1880s, by 1912, surface mining was conducted with steam shovels designed for coal mining. The most economical method of extraction from coal seams depends on the depth and quality of the seams. Coal mining processes are differentiated by whether they operate on the surface or underground, many coals extracted from both surface and underground mines require washing in a coal preparation plant. Surface mining and deep underground mining are the two methods of mining. Coal that occurs at depths of 180 to 300 ft are usually deep mined, for example, some western U. S. coal that occur at depths in excess of 200 ft are mined by the open pit methods, due to thickness of the seam 60–90 feet. Coals occurring below 300 ft are usually deep mined, However, there are open pit mining operations working on coal seams up to 1000–1500 feet below ground level, for instance Tagebau Hambach in Germany. When coal seams are near the surface, it may be economical to extract the coal using open cut mining methods, open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. In this mining method, explosives are first used in order to break through the surface or overburden, the overburden is then removed by draglines or by shovel and truck. Once the coal seam is exposed, it is drilled, fractured, the coal is then loaded onto large trucks or conveyors for transport to either the coal preparation plant or directly to where it will be used
Coal mining
–
A painting depicting men leaving a UK colliery at the close of a shift.
Coal mining
–
Surface coal mining in
Wyoming in the United States.
Coal mining
–
A coal mine in
Bihar, India.
Coal mining
–
A coal mine in
Frameries, Belgium.
15.
Rock (geology)
–
Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
Rock (geology)
–
Balanced Rock stands in the
Garden of the Gods park in
Colorado Springs
Rock (geology)
–
Rock outcrop along a mountain creek near
Orosí,
Costa Rica.
Rock (geology)
–
Sample of igneous
gabbro
Rock (geology)
–
Sedimentary sandstone with iron oxide bands
16.
Siltstone
–
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones. Siltstone is a sedimentary rock. As its name implies, it is composed of silt sized particles. Siltstones differ significantly from sandstones due to their smaller pores and higher propensity for containing a significant clay fraction, although often mistaken as a shale, siltstone lacks the fissility and laminations which are typical of shale. Unless the siltstone is fairly shaly, stratification is likely to be obscure, mudstone or shale are rocks that contain mud, which is material that has a range of silt and clay. Siltstone is differentiated by having a majority silt, not clay, folk, R. L.1965, Petrology of sedimentary rocks PDF version. 2nd ed.1981, ISBN 0-914696-14-9 Williams, Howel, Francis J. Turner and Charles M. Gilbert,1954, Petrography, W. H. Freeman
Siltstone
–
Siltstone
Siltstone
–
Holtzclaw siltstone, Louisville, Kentucky
17.
Drill cuttings
–
Drill cuttings are the broken bits of solid material removed from a borehole drilled by rotary, percussion, or auger methods. Boreholes drilled in this way include oil or gas wells, water wells, the drill cuttings are commonly examined to make a record of the subsurface materials penetrated at various depths. In the oil industry, this is called a mud log. Drill cuttings can be separated from liquid drilling fluid by shale shakers, by centrifuges, or by cyclone separators, in cable-tool drilling, the drill cuttings are periodically bailed out of the bottom of the hole. In auger drilling, cuttings are carried to the surface on the auger flights, one drilling method that does not produce drill cuttings is core drilling, which instead produces solid cylinders of rock or soil. Cuttings are then studied by mud engineers and well loggers before proper disposal, burial is the placement of waste in man-made or natural excavations, such as pits or landfills. Burial is the most common onshore disposal technique used for disposing of drilling wastes, generally, the solids are buried in the same pit used for collection and temporary storage of the waste mud and cuttings after the liquid is allowed to evaporate. Pit burial is a low-cost, low-tech method that not require wastes to be transported away from the well site. Burial may be the most misunderstood or misapplied disposal technique, simply pushing the walls of the reserve pit over the drilled cuttings is generally not acceptable. The depth or placement of the cell is important. A moisture content limit should be established on the cuttings. In some oil field areas, large landfills are operated to dispose of oil field wastes from multiple wells, burial usually results in anaerobic conditions, which limits any further degradation when compared with wastes that are land-farmed or land-spread, where aerobic conditions predominate. The objective of applying drilling wastes to the land is to allow the soils naturally occurring microbial population to metabolize, transform, Land application is a form of bioremediation are described in a separate fact sheet. Several terms are used to describe this waste management approach, which can be considered both treatment and disposal, some practitioners do not follow the same terminology convention, and may interchange all three terms. Readers should focus on the rather than on the specific names given to each process. The exploration and production industry has used land farming to treat oily petroleum industry wastes for years, Land farming can be a relatively low-cost drilling waste management approach. Some studies indicate that land farming does not adversely affect soils and may benefit certain sandy soils by increasing their water-retaining capacity. Inorganic compounds and metals are diluted in the soil, and may also be incorporated into the matrix or may become less soluble through oxidation, precipitation, the attenuation of heavy metals can depend on clay content and cation-exchange capacity
Drill cuttings
–
This article needs more
links to other articles to help
integrate it into the encyclopedia. Please help improve this article by adding links
that are relevant to the context within the existing text. (December 2012)
18.
Oil well
–
An oil well is a boring in the Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is produced along with the oil, a well that is designed to produce mainly or only gas may be termed a gas well. The earliest known oil wells were drilled in China in 347 CE and these wells had depths of up to about 240 metres and were drilled using bits attached to bamboo poles. The oil was burned to evaporate brine and produce salt, by the 10th century, extensive bamboo pipelines connected oil wells with salt springs. The ancient records of China and Japan are said to contain allusions to the use of natural gas for lighting and heating. Petroleum was known as Burning water in Japan in the 7th century, arab and Persian chemists also distilled crude oil in order to produce flammable products for military purposes. Through Islamic Spain, distillation became available in Western Europe by the 12th century, some sources claim that from the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan, to produce naphtha for the petroleum industry. These places were described by Marco Polo in the 13th century, when Marco Polo in 1264 visited Baku, on the shores of the Caspian Sea, he saw oil being collected from seeps. He wrote that on the confines toward Geirgine there is a fountain from which oil springs in great abundance, in 1846, Baku the first ever well was drilled with percussion tools to a depth of 21 meters for oil exploration. In 1848, the first modern oil well was drilled on the Aspheron Peninsula north-east of Baku, the earliest oil wells in modern times were drilled percussively, by repeatedly raising and dropping a cable tool into the earth. In the 20th century, cable tools were replaced with rotary drilling. The record-depth Kola Borehole used non-rotary mud motor drilling to achieve a depth of over 12,000 metres, until the 1970s, most oil wells were vertical, although lithological and mechanical imperfections cause most wells to deviate at least slightly from true vertical. However, modern directional drilling technologies allow for strongly deviated wells which can, given sufficient depth and with the proper tools, before a well is drilled, a geologic target is identified by a geologist or geophysicist to meet the objectives of the well. For a production well, the target is picked to optimize production from the well, for an exploration or appraisal well, the target is chosen to confirm the existence of a viable hydrocarbon reservoir or to ascertain its extent. The target will be matched with a location, and a trajectory between the two will be designed. When the well path is identified, a team of geoscientists and these properties include pore pressure, fracture gradient, wellbore stability, porosity, permeability, lithology, faults, and clay content. The well is created by drilling a hole 12 cm to 1 meter in diameter into the earth with a rig that rotates a drill string with a bit attached. After the hole is drilled, sections of pipe, slightly smaller in diameter than the borehole, are placed in the hole
Oil well
–
The
pumpjack, such as this one located south of
Midland, Texas, is a common sight in
West Texas
Oil well
–
Bottom Part of an Oil Drilling Derrick in Brazoria County, Texas (Harry Walker Photograph, circa 1940)
Oil well
–
1904
oil well fire at Bibi-Eibat
Oil well
–
Well Casing
19.
Louisiana
–
Louisiana is a state located in the southern region of the United States. Louisiana is the 31st most extensive and the 25th most populous of the 50 United States and its capital is Baton Rouge and largest city is New Orleans. Louisiana is the state in the U. S. with political subdivisions termed parishes. The largest parish by population is East Baton Rouge Parish, Louisiana is bordered by Arkansas to the north, Mississippi to the east, Texas to the west, and the Gulf of Mexico to the south. Much of the lands were formed from sediment washed down the Mississippi River, leaving enormous deltas and vast areas of coastal marsh. These contain a rich southern biota, typical examples include birds such as ibis, there are also many species of tree frogs, and fish such as sturgeon and paddlefish. In more elevated areas, fire is a process in the landscape. These support a large number of plant species, including many species of orchids. Louisiana has more Native American tribes than any other state, including four that are federally recognized, ten that are state recognized. Before the American purchase of the territory in 1803, the current Louisiana State had been both a French colony and for a period, a Spanish one. In addition, colonists imported numerous African people as slaves in the 18th century, many came from peoples of the same region of West Africa, thus concentrating their culture. Louisiana was named after Louis XIV, King of France from 1643 to 1715, when René-Robert Cavelier, Sieur de La Salle claimed the territory drained by the Mississippi River for France, he named it La Louisiane. The suffix -ana is a Latin suffix that can refer to information relating to an individual, subject. Thus, roughly, Louis + ana carries the idea of related to Louis, the Gulf of Mexico did not exist 250 million years ago when there was but one supercontinent, Pangea. As Pangea split apart, the Atlantic Ocean and Gulf of Mexico opened, Louisiana slowly developed, over millions of years, from water into land, and from north to south. The oldest rocks are exposed in the north, in such as the Kisatchie National Forest. The oldest rocks date back to the early Tertiary Era, some 60 million years ago, the history of the formation of these rocks can be found in D. Spearings Roadside Geology of Louisiana. The sediments were carried north to south by the Mississippi River
Louisiana
–
Louisiana entrance sign off
Interstate 20 in
Madison Parish east of
Tallulah.
Louisiana
–
Flag
Louisiana
–
Aerial view of Louisiana wetland habitats.
Louisiana
–
A field of yellow wildflowers in
Saint Bernard Parish, Louisiana
20.
United States
–
Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
United States
–
Native Americans meeting with Europeans, 1764
United States
–
Flag
United States
–
The signing of the
Mayflower Compact, 1620.
United States
–
The
Declaration of Independence: the
Committee of Five presenting their draft to the
Second Continental Congress in 1776
21.
Redox
–
Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
Redox
–
Rusting iron
Redox
–
A
bonfire
Redox
–
Oxides, such as
iron(III) oxide or
rust, which consists of hydrated
iron(III) oxides Fe 2 O 3 · n H 2 O and
iron(III) oxide-hydroxide (FeO(OH), Fe(OH) 3), form when oxygen combines with other elements
Redox
–
Iron rusting in
pyrite cubes
22.
Hematite
–
Hematite, also spelled as haematite, is the mineral form of iron oxide, one of several iron oxides. Hematite crystallizes in the lattice system, and it has the same crystal structure as ilmenite. Hematite and ilmenite form a solid solution at temperatures above 950 °C. Hematite is colored black to steel or silver-gray, brown to reddish brown and it is mined as the main ore of iron. Varieties include kidney ore, martite, iron rose and specularite, while the forms of hematite vary, they all have a rust-red streak. Hematite is harder than iron, but much more brittle. Maghemite is a hematite- and magnetite-related oxide mineral, huge deposits of hematite are found in banded iron formations. Gray hematite is typically found in places that can have still standing water or mineral hot springs, the mineral can precipitate out of water and collect in layers at the bottom of a lake, spring, or other standing water. Hematite can also occur without water, however, usually as the result of volcanic activity, the name hematite is derived from the Greek word for blood αἷμα haima, due to the red coloration found in some varities of hematite. The color of hematite lends itself to use as a pigment, ochre is a clay that is colored by varying amounts of hematite, varying between 20% and 70%. Red ochre contains unhydrated hematite, whereas yellow ochre contains hydrated hematite, the principal use of ochre is for tinting with a permanent color. The red chalk writing of this mineral was one of the earliest in the history of humans, the powdery mineral was first used 164,000 years ago by the Pinnacle-Point man possibly for social purposes. Hematite residues are found in graves from 80,000 years ago. Near Rydno in Poland and Lovas in Hungary red chalk mines have been found that are from 5000 BC, rich deposits of hematite have been found on the island of Elba that have been mined since the time of the Etruscans. Adding to the surprise was a transition with a decrease in temperature at around 260 K to a phase with no net magnetic moment. The disappearance of the moment with a decrease in temperature at 260 K is caused by a change in the anisotropy which causes the moments to align along the c axis, in this configuration, spin canting does not reduce the energy. The magnetic properties of bulk hematite differ from their nanoscale counterparts, for example, the Morin transition temperature of hematite decreases with a decrease in the particle size. Two other end-members are referred to as protohematite and hydrohematite, enhanced magnetic coercivities for hematite have been achieved by dry-heating a 2-line ferrihydrite precursor prepared from solution
Hematite
–
Brazilian
trigonal hematite crystal
Hematite
–
Crystal structure of hematite
Hematite
–
Image mosaic from the Mars Exploration Rover Microscopic Imager shows Hematite
spherules partly embedded in rock at the Opportunity landing site. Image is ca. 5 cm (2 in) across.
Hematite
–
Hematite carving, 5 cm (2 in) long.
23.
Goethite
–
Goethite, is an iron bearing hydroxide mineral of the diaspore group, is found in soil and other low-temperature environments. Goethite has been known since ancient times for its use as a pigment. Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux in France and it was first described in 1806 based on samples found in the Hollertszug Mine in Herdorf, Germany. The mineral was named after the German polymath and poet Johann Wolfgang von Goethe, in 2003, nanoparticulate authigenic goethite was shown to be the most common diagenetic iron oxyhydroxide in both marine and lake sediments. Goethite is an iron oxyhydroxide containing ferric iron and it is the main component of rust and bog iron ore. Goethites hardness ranges from 5.0 to 5.5 on the Mohs Scale, the mineral forms prismatic needle-like crystals, but is more typically massive. Feroxyhyte and lepidocrocite are both polymorphs of the iron oxyhydroxide FeO, although they have the same chemical formula as goethite, their different crystalline structures make them distinct minerals. Goethite often forms through the weathering of other minerals, and thus is a common component of soils. The formation of goethite is marked by the state change of Fe2+ to Fe3+. Because of this state change, goethite is commonly seen as a pseudomorph. As iron-bearing minerals are brought to the zone of oxidation within the soil and it may also be precipitated by groundwater or in other sedimentary conditions, or form as a primary mineral in hydrothermal deposits. Goethite has also found to be produced by the excretion processes of certain bacteria types. Goethite is found all over the planet, usually in the form of concretions, stalactitic formations, oolites and it is also a very common pseudomorph. It is frequently encountered in the areas at the head of spring waters, on cave floors. The boxworks or gossan resulting from the oxidation of ore deposits is formed of goethite along with other iron oxides. Significant deposits of goethite are found in England, Australia, Cuba, and Michigan, Minnesota, Missouri, Colorado, Alabama, Georgia, Virginia, and Tennessee, and Florida caves in the United States. In 2015 it was reported that limpets teeth have goethite fibres in them and its main modern use is as an iron ore, being referred to as brown iron ore. It does have some use as an earth pigment
Goethite
–
Goethite, Restormel Royal Iron Mine, Cornwall, England.
Goethite
–
Unusual specimen of Goethite replacing a
gypsum stalactite; the center is hollow. From
Santa Eulalia, Chihuahua, Mexico.
Goethite
–
Goethite coating/replacing rusted
pyrite cubes.
24.
Limonite
–
Limonite is an iron ore consisting of a mixture of hydrated iron oxide-hydroxides in varying composition. The generic formula is written as FeO·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the two principal iron ores, the other being hematite, and has been mined for the production of iron since at least 2500 BCE. Limonite is named from the Greek word for meadow, in allusion to its occurrence as bog ore in meadows. In its brown form it is called brown hematite or brown iron ore. In its bright yellow form it is sometimes called lemon rock or yellow iron ore, limonite is relatively dense with a specific gravity varying from 2.7 to 4.3. It varies in colour from a bright yellow to a drab greyish brown. The streak of limonite on a porcelain plate is always brownish. The hardness is variable, but generally in the 4 -5.5 range, although originally defined as a single mineral, limonite is now recognized as a mixture of related hydrated iron oxide minerals, among them goethite, akaganeite, lepidocrocite, and jarosite. Because of its amorphous nature, and occurrence in hydrated areas limonite often presents as a clay or mudstone, however, there are limonite pseudomorphs after other minerals such as pyrite. This means that chemical weathering transforms the crystals of pyrite into limonite by hydrating the molecules, limonite pseudomorphs have also been formed from other iron oxides, hematite and magnetite, from the carbonate siderite and from iron rich silicates such as almandine garnets. It is often the major component in lateritic soils. It is often deposited in run-off streams from mining operations, one of the first uses was as a pigment. The yellow form produced yellow ochre for which Cyprus was famous, roasting the limonite changed it partially to hematite, producing red ochres, burnt umbers and siennas. Bog iron ore and limonite mudstones are mined as a source of iron, Iron caps or gossans of siliceous iron oxide typically form as the result of intensive oxidation of sulfide ore deposits. These gossans were used by prospectors as guides to buried ore, in addition the oxidation of those sulfide deposits which contained gold, often resulted in the concentration of gold in the iron oxide and quartz of the gossans. Goldbearing limonite gossans were mined in the Shasta County, California mining district. Similar deposits were mined near Rio Tinto in Spain and Mount Morgan in Australia, in the Dahlonega gold belt in Lumpkin County, Georgia gold was mined from limonite-rich lateritic or saprolite soil
Limonite
–
Limonite
Limonite
–
Bog ore
Limonite
–
Limonite deposited from mine runoff
Limonite
–
Galena and Limonite
25.
Chlorite group
–
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the four elements in the silicate lattice, Mg, Fe, Ni. Clinochlore, O108 Chamosite, O108 Nimite, O108 Pennantite, 64O108 In addition, zinc, lithium, the great range in composition results in considerable variation in physical, optical, and X-ray properties. Similarly, the range of chemical composition allows chlorite group minerals to exist over a range of temperature and pressure conditions. For this reason chlorite minerals are ubiquitous minerals within low and medium temperature metamorphic rocks, some rocks, hydrothermal rocks. The name chlorite is from the Greek chloros, meaning green, the typical general formula is, 34O102·36. This formula emphasizes the structure of the group, chlorites have a 2,1 sandwich structure, this is often referred to as a talc layer. Unlike other 2,1 clay minerals, a chlorites interlayer space is composed of 6 and this 6 unit is more commonly referred to as the brucite-like layer, due to its closer resemblance to the mineral brucite. Therefore, chlorites structure appears as follows, -t-o-t-brucite-t-o-t-brucite, thats why they are also called 2,1,1 minerals. An older classification divided the chlorites into two subgroups, the orthochlorites and leptochlorites, the terms are seldom used and the ortho prefix is somewhat misleading as the chlorite crystal system is monoclinic and not orthorhombic. Chlorite is commonly found in rocks as an alteration product of mafic minerals such as pyroxene, amphibole. Chlorite is a common mineral associated with ore deposits and commonly occurs with epidote, sericite, adularia. Chlorite is also a metamorphic mineral, usually indicative of low-grade metamorphism. It is the species of the zeolite facies and of lower greenschist facies. It occurs in the quartz, albite, sericite, chlorite, within ultramafic rocks, metamorphism can also produce predominantly clinochlore chlorite in association with talc. Chlorite occurs naturally in a variety of locations and forms, for example, chlorite is found naturally in certain parts of Wales in mineral schists. Chlorite is found in large boulders scattered on the surface on Ring Mountain in Marin County. Clinoclore, pennantite, and chamosite are the most common varieties, several other sub-varieties have been described
Chlorite group
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Chlorite group
Chlorite group
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Quartz crystal with chlorite inclusions from
Minas Gerais,
Brazil (size: 4.2 × 3.9 × 3.3 cm)
Chlorite group
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Chlorite
pseudomorph after
garnet from Michigan (size: 3.5 × 3.1 × 2.7 cm)
Chlorite group
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Chlorite schist
26.
Biotite
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Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K 3AlSi 3O102. Hausmann in 1847 in honor of the French physicist Jean-Baptiste Biot, iron, magnesium, aluminium, silicon, oxygen, and hydrogen form sheets that are weakly bound together by potassium ions. It is sometimes called iron mica because it is more iron-rich than phlogopite and it is also sometimes called black mica as opposed to white mica – both form in some rocks, and in some instances side-by-side. Like other mica minerals, biotite has a perfect basal cleavage, and consists of flexible sheets, or lamellae. It has a crystal system, with tabular to prismatic crystals with an obvious pinacoid termination. It has four faces and two pinacoid faces to form a pseudohexagonal crystal. Although not easily seen because of the cleavage and sheets, fracture is uneven and it appears greenish to brown or black, and even yellow when weathered. It can be transparent to opaque, has a vitreous to pearly luster, when biotite is found in large chunks, they are called “books” because it resembles a book with pages of many sheets. The color of biotite is usually black and the mineral has a hardness of 2. 5-3 on the Mohs scale of mineral hardness, biotite dissolves in both acid and alkaline aqueous solutions, with the highest dissolution rates at low pH. However, biotite dissolution is highly anisotropic with crystal edge surfaces reacting 45 to 132 times faster than basal surfaces, under cross-polarized light biotite can generally be identified by the gnarled birds eye extinction. Biotite is found in a variety of igneous and metamorphic rocks. For instance, biotite occurs in the lava of Mount Vesuvius, biotite in granite tends to be poorer in magnesium than the biotite found in its volcanic equivalent, rhyolite. Biotite is an essential phenocryst in some varieties of lamprophyre, biotite is occasionally found in large cleavable crystals, especially in pegmatite veins, as in New England, Virginia and North Carolina. Other notable occurrences include Bancroft and Sudbury, Ontario and it is an essential constituent of many metamorphic schists, and it forms in suitable compositions over a wide range of pressure and temperature. It has been estimated that biotite comprises up to 7% of the continental crust. The largest documented single crystals of biotite were approximately 7 m2 sheets found in Iveland, biotite is used extensively to constrain ages of rocks, by either potassium-argon dating or argon-argon dating. Because argon escapes readily from the crystal structure at high temperatures. Biotite is also useful in assessing temperature histories of metamorphic rocks, because the partitioning of iron and magnesium between biotite and garnet is sensitive to temperature
Biotite
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Thin tabular biotite aggregate (Image width: 2.5 mm)
27.
Illite
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Illite is a non-expanding clay crystalline mineral. Illite is a secondary mineral precipitate phyllosilicate or layered alumino-silicate and its structure is a 2,1 clay of silica tetrahedron – alumina octahedron – silica tetrahedron layers. The space between individual clay crystals is occupied by poorly hydrated potassium cations which is responsible for the absence of swelling, structurally, illite is quite similar to muscovite with slightly more silicon, magnesium, iron, and water and slightly less tetrahedral aluminium and interlayer potassium. The chemical formula is given as 24O10, but there is considerable ion substitution and it occurs as aggregates of small monoclinic grey to white crystals. Due to the size, positive identification usually requires x-ray diffraction or SEM-EDS analysis. Illite occurs as a product of muscovite and feldspar in weathering and hydrothermal environments. It is common in sediments, soils, and argillaceous sedimentary rocks as well as in low grade metamorphic rocks. The iron rich member of the group, glauconite, in sediments can be differentiated by x-ray analysis. The cation-exchange capacity of illite is smaller than that of smectite but higher than that of kaolinite, illite was first described for occurrences in the Maquoketa shale in Calhoun County, Illinois, US, in 1937. The name was derived from its location in Illinois. Illite is also called hydromica or hydromuscovite, brammallite is a sodium rich analogue. Avalite is a chromium bearing variety which has been described form Mt. Avala, Belgrade, the crystallinity of illite has been used as an indicator of metamorphic grade in clay-bearing rocks metamorphosed under conditions between diagenesis and low-grade metamorphism. With increasing temperature, illite is thought to undergo a transformation into muscovite,437 pp, see Chapter 3, Soil Mineralogy, p.32
Illite
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Illite
Illite
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Structure of Illite mica - USGS.
28.
Kaolinite
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Kaolinite /ˈkeɪəlᵻˌnaɪt/ is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O54. It is a silicate mineral, with one tetrahedral sheet of silica linked through oxygen atoms to one octahedral sheet of alumina octahedra. Rocks that are rich in kaolinite are known as kaolin /ˈkeɪəlᵻn/ or china clay, the name kaolin is derived from Gaoling, a Chinese village near Jingdezhen in southeastern Chinas Jiangxi Province. The name entered English in 1727 from the French version of the word, kaolin, kaolinite has a low shrink–swell capacity and a low cation-exchange capacity. It is a soft, earthy, usually white, mineral, in many parts of the world it is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lighter concentrations yield white, yellow, or light orange colors, alternating layers are sometimes found, as at Providence Canyon State Park in Georgia, United States. Commercial grades of kaolin are supplied and transported as dry powder, kaolinite group clays undergo a series of phase transformations upon thermal treatment in air at atmospheric pressure. Below 100 °C, exposure to dry air will slowly remove liquid water from the kaolin, the end-state for this transformation is referred to as leather dry. Between 100 °C and about 550 °C, any remaining water is expelled from kaolinite. The end state for this transformation is referred to as bone dry, throughout this temperature range, the expulsion of water is reversible, if the kaolin is exposed to liquid water, it will be reabsorbed and disintegrate into its fine particulate form. Subsequent transformations are not reversible, and represent permanent chemical changes, endothermic dehydration of kaolinite begins at 550–600 °C producing disordered metakaolin, but continuous hydroxyl loss is observed up to 900 °C. Al2Si2O54 → Al2Si2O7 +2 H2O, further heating to 925–950 °C converts metakaolin to an aluminium-silicon spinel which is sometimes also referred to as a gamma-alumina type structure,2 Al2Si2O7 → Si3Al4O12 + SiO2. Upon calcination above 1050 °C, the spinel phase nucleates and transforms to platelet mullite, finally, at 1400 °C the needle form of mullite appears, offering substantial increases in structural strength and heat resistance. This is a structural but not chemical transformation, see stoneware for more information on this form. Kaolinite clay occurs in abundance in soils that have formed from the weathering of rocks in hot. Such climatically-related differences in mineral content are often used to infer changes in climates in the geological past. In the Institut National pour lEtude Agronomique au Congo Belge classification system, in the US the main kaolin deposits are found in central Georgia, on a stretch of the Atlantic Seaboard fall line between Augusta and Macon. The deposits were formed between the late Cretaceous and early Paleogene, about 100 million to 45 million years ago, in sediments derived from weathered igneous, Kaolin production in the US during 2011 was 5.5 million tonnes
Kaolinite
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Kaolinite
Kaolinite
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Kaolinite structure
29.
Montmorillonite
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Montmorillonite is a very soft phyllosilicate group of minerals that form when they precipitate from water solution as microscopic crystals, known as clay. It is named after Montmorillon in France, montmorillonite, a member of the smectite group, is a 2,1 clay, meaning that it has two tetrahedral sheets of silica sandwiching a central octahedral sheet of alumina. Members of this group include saponite, the substitution of lower valence cations in such instances leaves the nearby oxygen atoms with a net negative charge that can attract cations. In contrast, beidellite is smectite with greater than 50% tetrahedral charge originating from isomorphous substitution of Al for Si in the silica sheet, the individual crystals of montmorillonite clay are not tightly bound hence water can intervene, causing the clay to swell. The water content of montmorillonite is variable and it greatly in volume when it absorbs water. Chemically, it is hydrated sodium calcium magnesium silicate hydroxide 0. 3322·nH2O. Potassium, iron, and other cations are common substitutes, and it often occurs intermixed with chlorite, muscovite, illite, cookeite, and kaolinite. Montmorillonite can be concentrated and transformed within cave environments, the natural weathering of the cave can leave behind concentrations of aluminosilicates which were contained within the bedrock. Montmorillonite can form slowly in solutions of aluminosilicates, high HCO3 concentrations and long periods of time can aid in its formation. Montmorillonite can then transform to palygorskite under dry conditions and to halloysite-10Å in acidic conditions, halloysite-10Å can further transform into halloysite-7Å by drying. Montmorillonite is used in the oil drilling industry as a component of drilling mud, making the mud slurry viscous, which helps in keeping the drill bit cool and removing drilled solids. It is also used as an additive to hold soil water in drought-prone soils, used in the construction of earthen dams and levees. It is also used as a component of sand and as a desiccant to remove moisture from air. Montmorillonite clays have been used in catalytic processes. Cracking catalysts have used montmorillonite clays for over 60 years, other acid-based catalysts use acid-treated montmorillonite clays. Similar to many other clays, montmorillonite swells with the addition of water, montmorillonites expand considerably more than other clays due to water penetrating the interlayer molecular spaces and concomitant adsorption. The amount of expansion is due largely to the type of exchangeable cation contained in the sample, the presence of sodium as the predominant exchangeable cation can result in the clay swelling to several times its original volume. This swelling property makes montmorillonite-containing bentonite useful also as a seal or plug for water wells
Montmorillonite
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A sample of montmorillonite (unknown scale)
30.
Smectite
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Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life and they are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Clays form flat hexagonal sheets similar to the micas, Clay minerals are common weathering products and low-temperature hydrothermal alteration products. Clay minerals are common in soils, in fine-grained sedimentary rocks such as shale, mudstone. Clay minerals are usually ultrafine-grained and so may require special techniques for their identification. These methods can be augmented by polarized light microscopy, a traditional technique establishing fundamental occurrences or petrologic relationships. Given the requirement of water, clay minerals are rare in the Solar System, though they occur extensively on Earth where water has interacted with other minerals. Clay minerals have been detected at several locations on Mars including Echus Chasma and Mawrth Vallis and the Memnonia quadrangle, spectrography has confirmed their presence on asteroids including the dwarf planet Ceres and Tempel 1 as well as Jupiters moon Europa. A1,1 clay would consist of one sheet and one octahedral sheet. A2,1 clay consists of an octahedral sheet sandwiched between two sheets, and examples are talc, vermiculite and montmorillonite. Smectite group which includes dioctahedral smectites such as montmorillonite, nontronite and beidellite, in 2013, analytical tests by the Curiosity rover found results consistent with the presence of smectite clay minerals on the planet Mars. Illite group which includes the clay-micas, illite is the only common mineral. Chlorite group includes a variety of similar minerals with considerable chemical variation. Other 2,1 clay types exist such as sepiolite or attapulgite, mixed layer clay variations exist for most of the above groups. Ordering is described as random or regular ordering, and is described by the term reichweite. Literature articles will refer to a R1 ordered illite-smectite, for example and this type would be ordered in an ISISIS fashion. R0 on the other hand describes random ordering, and other advanced ordering types are also found, mixed layer clay minerals which are perfect R1 types often get their own names. R1 ordered chlorite-smectite is known as corrensite, R1 illite-smectite is rectorite, knowledge of the nature of clay became better understood in the 1930s with advancements in x-ray diffraction technology necessary to analyze the molecular nature of clay particles
Smectite
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Oxford Clay (
Jurassic) exposed near
Weymouth, England.
