Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and silt. The dominant carbonate mineral in most marls is calcite, but other carbonate minerals such as aragonite and siderite may be present. Marl was an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay and calcium carbonate, formed under freshwater conditions, it describes a habit of coralline red alga. The term is today used to describe indurated marine deposits and lacustrine sediments which more should be named'marlstone'. Marlstone is an indurated rock of about the same composition as marl, more called an earthy or impure argillaceous limestone, it has a blocky subconchoidal fracture, is less fissile than shale. The term'marl' is used in English-language geology, while the terms Mergel and Seekreide are used in European references; the lower stratigraphic units of the chalk cliffs of Dover consist of a sequence of glauconitic marls followed by rhythmically banded limestone and marl layers.
Upper Cretaceous cyclic sequences in Germany and marl–opal-rich Tortonian-Messinian strata in the Sorbas basin related to multiple sea drawdown have been correlated with Milankovitch orbital forcing. Marl as lacustrine sediment is common in post-glacial lake-bed sediments found underlying peat bogs, it has been used as acid soil neutralizing agent. Marl was extensively mined in Central New Jersey as a soil conditioner in the 1800s. In 1863, the most common marl was blue marl. While the specific composition and properties of the marl varied depending on what layer it was found in, blue marl was composed of 38.70% silicic acid and sand, 30.67% oxide of iron, 13.91% carbonate of lime, 11.22% water, 4.47% potash, 1.21% magnesia, 1.14% phosphoric acid, 0.31% sulphuric acid. Marl was in high demand for farms. An example of the amount of marl mined comes from a report from 1880, from Marlboro, Monmouth County, New Jersey, which reported the following tons of marl sold during the year: OC Herbert Marl Pit – 9961 tons Uriah Smock Marl Pit – 4750 tons CM Conover Marl Pit – 760 tonsIn the Centennial Exhibition report in 1877, marl is described in many different forms and came from 69 marl pits in and around New Jersey.
The report identified a number of agricultural marls types, including clay marl, blue marl, red marl, high bank marl, shell layer marl, under shell layer marl, sand marl, green marl, gray marl, clayey marl. Agricultural lime D. Russell, J. and Kerry Kelts. 2003. Classification of lacustrine sediments based on sedimentary components. Journal of Paleolimnology 29: 141–154. Chalk of Kent by C. S. Harris Geochemistry and time-series analyses of orbitally forced Upper Cretaceous marl–limestone rhythmites, abstract Palaeoenvironmental Interpretation of the Early Postglacial Sedimentary Record of a Marl Lake
The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals or clasts are embedded. The matrix of an igneous rock consists of finer-grained microscopic, crystals in which larger crystals are embedded; this porphyritic texture is indicative of multi-stage cooling of magma. For example, porphyritic andesite will have large phenocrysts of plagioclase in a fine-grained matrix. In South Africa, diamonds are mined from a matrix of weathered clay-like rock called "yellow ground"; the matrix of sedimentary rocks is finer-grained sedimentary material, such as clay or silt, in which larger grains or clasts are embedded. It is used to describe the rock material in which a fossil is embedded. All sediments are at first in an incoherent condition, they may remain in this state for an indefinite period. Millions of years have elapsed since some of the early Tertiary strata gathered on the ocean floor, yet they are quite friable and differ little from many recent accumulations.
There are few exceptions, however, to the rule that with increasing age sedimentary rocks become more and more indurated, the older they are the more it is that they will have the firm consistency implied in the term "rock". The pressure of newer sediments on underlying masses is one cause of this change, though not in itself a powerful one. More efficiency is ascribed to the action of percolating water, which takes up certain soluble materials and redeposits them in pores and cavities; this operation is accelerated by the increased pressure produced by superincumbent masses, to some extent by the rise of temperature which takes place in rocks buried to some depth beneath the surface. The rise of temperature, however, is never great; the redeposited cementing material is most calcareous or siliceous. Limestones, which were a loose accumulation of shells, etc. become compacted into firm rock in this manner. The cementing substance may be deposited in crystalline continuity on the original grains, where these were crystalline, in sandstones, a crystalline matrix of calcite envelops the sand grains.
The change of aragonite to calcite and of calcite to dolomite, by forming new crystalline masses in the interior of the rock also accelerates consolidations. Silica is less soluble in ordinary waters, but this ingredient of rocks is dissolved and redeposited with great frequency. Many sandstones are held together by an infinitesimal amount of cryptocrystalline silica. Others contain fine scales of mica. Argillaceous materials may be compacted by mere pressure, like graphite and other scaly minerals
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite and is the main component of pearls and the shells of marine organisms and eggs. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale, it is medicinally used as a calcium supplement or as an antacid, but excessive consumption can be hazardous. Calcium carbonate shares the typical properties of other carbonates. Notably it reacts with acids, releasing carbon dioxide:CaCO3 + 2 H+ → Ca2+ + CO2 + H2Oreleases carbon dioxide upon heating, called a thermal decomposition reaction, or calcination, to form calcium oxide called quicklime, with reaction enthalpy 178 kJ/mol:CaCO3 → CaO + CO2Calcium carbonate will react with water, saturated with carbon dioxide to form the soluble calcium bicarbonate. CaCO3 + CO2 + H2O → Ca2This reaction is important in the erosion of carbonate rock, forming caverns, leads to hard water in many regions.
An unusual form of calcium carbonate is the hexahydrate, ikaite, CaCO3·6H2O. Ikaite is stable only below 8 °C; the vast majority of calcium carbonate used in industry is extracted by quarrying. Pure calcium carbonate, can be produced from a pure quarried source. Alternatively, calcium carbonate is prepared from calcium oxide. Water is added to give calcium hydroxide carbon dioxide is passed through this solution to precipitate the desired calcium carbonate, referred to in the industry as precipitated calcium carbonate: CaO + H2O → Ca2 Ca2 + CO2 → CaCO3↓ + H2O The thermodynamically stable form of CaCO3 under normal conditions is hexagonal β-CaCO3. Other forms can be prepared, the denser orthorhombic λ-CaCO3 and μ-CaCO3, occurring as the mineral vaterite; the aragonite form can be prepared by precipitation at temperatures above 85 °C, the vaterite form can be prepared by precipitation at 60 °C. Calcite contains calcium atoms coordinated by six oxygen atoms, in aragonite they are coordinated by nine oxygen atoms.
The vaterite structure is not understood. Magnesium carbonate has the calcite structure, whereas strontium carbonate and barium carbonate adopt the aragonite structure, reflecting their larger ionic radii. Calcite and vaterite are pure calcium carbonate minerals. Industrially important source rocks which are predominantly calcium carbonate include limestone, chalk and travertine. Eggshells, snail shells and most seashells are predominantly calcium carbonate and can be used as industrial sources of that chemical. Oyster shells have enjoyed recent recognition as a source of dietary calcium, but are a practical industrial source. Dark green vegetables such as broccoli and kale contain dietarily significant amounts of calcium carbonate, they are not practical as an industrial source. Beyond Earth, strong evidence suggests the presence of calcium carbonate on Mars. Signs of calcium carbonate have been detected at more than one location; this provides some evidence for the past presence of liquid water.
Carbonate, is found in geologic settings and constitutes an enormous carbon reservoir. Calcium carbonate occurs as aragonite and dolomite as significant constituents of the calcium cycle; the carbonate minerals form the rock types: limestone, marble, travertine and others. In warm, clear tropical waters corals are more abundant than towards the poles where the waters are cold. Calcium carbonate contributors, including plankton, coralline algae, brachiopods, echinoderms and mollusks, are found in shallow water environments where sunlight and filterable food are more abundant. Cold-water carbonates do exist at higher latitudes but have a slow growth rate; the calcification processes are changed by ocean acidification. Where the oceanic crust is subducted under a continental plate sediments will be carried down to warmer zones in the asthenosphere and lithosphere. Under these conditions calcium carbonate decomposes to produce carbon dioxide which, along with other gases, give rise to explosive volcanic eruptions.
The carbonate compensation depth is the point in the ocean where the rate of precipitation of calcium carbonate is balanced by the rate of dissolution due to the conditions present. Deep in the ocean, the temperature pressure increases. Calcium carbonate is unusual in. Increasing pressure increases the solubility of calcium carbonate; the carbonate compensation depth can range from 4,000 to 6,000 meters below sea level. Calcium carbonate can preserve fossils through permineralization. Most of the vertebrate fossils of the Two Medicine Formation—a geologic formation known for its duck-billed dinosaur eggs—are preserved by CaCO3 permineralization; this type of preservation conserves high levels of detail down to the microscopic level. However, it leaves specimens vulnerable to weathering when exposed to the surface. Trilobite populations were once thought to have composed the majority of aquatic life during the Cambrian, due to the fact that their calcium carbonate-rich shells were more preserved than those of other species, which had purely chitinous shells.
The main use of calcium ca
The micrometre or micrometer commonly known by the previous name micron, is an SI derived unit of length equalling 1×10−6 metre. The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, for grading wool by the diameter of the fibres; the width of a single human hair ranges from 10 to 200 μm. The longest human chromosome is 10 μm in length. Between 1 μm and 10 μm: 1–10 μm – length of a typical bacterium 10 μm – Size of fungal hyphae 5 μm – length of a typical human spermatozoon's head 3–8 μm – width of strand of spider web silk about 10 μm – size of a fog, mist, or cloud water droplet Between 10 μm and 100 μm about 10–12 μm – thickness of plastic wrap 10 to 55 μm – width of wool fibre 17 to 181 μm – diameter of human hair 70 to 180 μm – thickness of paper The term micron and the symbol μ were accepted for use in isolation to denote the micrometre in 1879, but revoked by the International System of Units in 1967; this became necessary because the older usage was incompatible with the official adoption of the unit prefix micro-, denoted μ, during the creation of the SI in 1960.
In the SI, the systematic name micrometre became the official name of the unit, μm became the official unit symbol. In practice, "micron" remains a used term in preference to "micrometre" in many English-speaking countries, both in academic science and in applied science and industry. Additionally, in American English, the use of "micron" helps differentiate the unit from the micrometer, a measuring device, because the unit's name in mainstream American spelling is a homograph of the device's name. In spoken English, they may be distinguished by pronunciation, as the name of the measuring device is invariably stressed on the second syllable, whereas the systematic pronunciation of the unit name, in accordance with the convention for pronouncing SI units in English, places the stress on the first syllable; the plural of micron is "microns", though "micra" was used before 1950. The official symbol for the SI prefix micro- is a Greek lowercase mu. In Unicode, there is a micro sign with the code point U+00B5, distinct from the code point U+03BC of the Greek letter lowercase mu.
According to the Unicode Consortium, the Greek letter character is preferred, but implementations must recognize the micro sign as well. Most fonts use the same glyph for the two characters. Metric prefix Metric system Orders of magnitude Wool measurement The dictionary definition of micrometre at Wiktionary
Sandstone is a clastic sedimentary rock composed of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds form visible cliffs and other topographic features, certain colors of sandstone have been identified with certain regions. Rock formations that are composed of sandstone allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be changed into quartzite through metamorphism related to tectonic compression within orogenic belts.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals; the cements binding these grains together are calcite and silica. Grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are called argillaceous sediments; the formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Sedimentation occurs by the sand settling out from suspension. Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains; the most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried.
Colors will be tan or yellow. A predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe and Mongolia; the regularity of the latter favours use as a source for masonry, either as a primary building material or as a facing stone, over other forms of construction. The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings: Terrestrial environmentsRivers Alluvial fans Glacial outwash Lakes Deserts Marine environmentsDeltas Beach and shoreface sands Tidal flats Offshore bars and sand waves Storm deposits Turbidites Framework grains are sand-sized detrital fragments that make up the bulk of a sandstone.
These grains can be classified into several different categories based on their mineral composition: Quartz framework grains are the dominant minerals in most clastic sedimentary rocks. These physical properties allow the quartz grains to survive multiple recycling events, while allowing the grains to display some degree of rounding. Quartz grains evolve from plutonic rock, which are felsic in origin and from older sandstones that have been recycled. Feldspathic framework grains are the second most abundant mineral in sandstones. Feldspar can be divided into two smaller subdivisions: plagioclase feldspars; the different types of feldspar can be distinguished under a petrographic microscope. Below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the chemical composition of the mineral can range from KAlSi3O8 to NaAlSi3O8, this represents a complete solid solution. Plagioclase feldspar is a complex group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8.
Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, called lithic fragments or clasts. Lithic fragments can be any fine-grained or coarse-grained igneous, metamorphic, or sedimentary rock, although the most common lithic fragments found in sedimentary rocks are clasts of volcanic rocks. Accessory minerals are all other mineral grains in a sandstone. Common accessory minerals include micas, olivine and corundum. Many of these accessory grains are more dense than the silicates that
A mineral is, broadly speaking, a solid chemical compound that occurs in pure form. A rock may consist of a single mineral, or may be an aggregate of two or more different minerals, spacially segregated into distinct phases. Compounds that occur only in living beings are excluded, but some minerals are biogenic and/or are organic compounds in the sense of chemistry. Moreover, living beings synthesize inorganic minerals that occur in rocks. In geology and mineralogy, the term "mineral" is reserved for mineral species: crystalline compounds with a well-defined chemical composition and a specific crystal structure. Minerals without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound may occur with different crystal structures, each structure is considered different mineral species. Thus, for example and stishovite are two different minerals consisting of the same compound, silicon dioxide; the International Mineralogical Association is the world's premier standard body for the definition and nomenclature of mineral species.
As of November 2018, the IMA recognizes 5,413 official mineral species. Out of more than 5,500 proposed or traditional ones; the chemical composition of a named mineral species may vary somewhat by the inclusion of small amounts of impurities. Specific varieties of a species sometimes have official names of their own. For example, amethyst is a purple variety of the mineral species quartz; some mineral species can have variable proportions of two or more chemical elements that occupy equivalent positions in the mineral's structure. Sometimes a mineral with variable composition is split into separate species, more or less arbitrarily, forming a mineral group. Besides the essential chemical composition and crystal structure, the description of a mineral species includes its common physical properties such as habit, lustre, colour, tenacity, fracture, specific gravity, fluorescence, radioactivity, as well as its taste or smell and its reaction to acid. Minerals are classified by key chemical constituents.
Silicate minerals comprise 90% of the Earth's crust. Other important mineral groups include the native elements, oxides, carbonates and phosphates. One definition of a mineral encompasses the following criteria: Formed by a natural process. Stable or metastable at room temperature. In the simplest sense, this means. Classical examples of exceptions to this rule include native mercury, which crystallizes at −39 °C, water ice, solid only below 0 °C. Modern advances have included extensive study of liquid crystals, which extensively involve mineralogy. Represented by a chemical formula. Minerals are chemical compounds, as such they can be described by fixed or a variable formula. Many mineral groups and species are composed of a solid solution. For example, the olivine group is described by the variable formula 2SiO4, a solid solution of two end-member species, magnesium-rich forsterite and iron-rich fayalite, which are described by a fixed chemical formula. Mineral species themselves could have a variable composition, such as the sulfide mackinawite, 9S8, a ferrous sulfide, but has a significant nickel impurity, reflected in its formula.
Ordered atomic arrangement. This means crystalline. An ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form and cleavage. There have been several recent proposals to classify amorphous substances as minerals; the formal definition of a mineral approved by the IMA in 1995: "A mineral is an element or chemical compound, crystalline and, formed as a result of geological processes." Abiogenic. Biogenic substances are explicitly excluded by the IMA: "Biogenic substances are chemical compounds produced by biological processes without a geological component and are not regarded as minerals. However, if geological processes were involved in the genesis of the compound the product can be accepted as a mineral."The first three general characteristics are less debated than the last two. Mineral classification schemes and their definitions are evolving to match recent advances in mineral science. Recent changes have included the addition of an organic class, in both the new Dana and the Strunz classification schemes.
The organic class includes a rare group of minerals with hydrocarbons. The IMA Commission on New Minerals and Mineral Names adopted in 2009 a hierarchical scheme for the naming and classification of mineral groups and group names and established seven commissions and four working groups to review and classify minerals into an official listing of their published names. According to these new r
Montmorillonite is a 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; the particles are plate-shaped with a thickness of 0.96 nm. Members of this group include saponite. Montmorillonite is a subclass of smectite, a 2:1 phyllosilicate mineral characterized as having greater than 50% octahedral charge; 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 bound hence water can intervene, causing the clay to swell. The water content of montmorillonite is variable and it increases in volume when it absorbs water.
Chemically, it is hydrated sodium calcium aluminium magnesium silicate hydroxide 0.3322·nH2O. Potassium and other cations are common substitutes, the exact ratio of cations varies with source, it occurs intermixed with chlorite, illite and kaolinite. Montmorillonite can be 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 in solutions of aluminosilicates. High HCO3 - concentrations and long periods of time can aid in its formation. Montmorillonite can 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 used as a soil additive to hold soil water in drought-prone soils, used in the construction of earthen dams and levees, to prevent the leakage of fluids.
It is used as a component of foundry sand and as a desiccant to remove moisture from air and gases. Montmorillonite clays have been extensively 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 more than other clays due to water penetrating the interlayer molecular spaces and concomitant adsorption; the amount of expansion is due 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. Hence, sodium montmorillonite has come to be used as the major constituent in nonexplosive agents for splitting rock in natural stone quarries in an effort to limit the amount of waste, or for the demolition of concrete structures where the use of explosive charges is unacceptable.
This swelling property makes montmorillonite-containing bentonite useful as an annular seal or plug for water wells and as a protective liner for landfills. Other uses include as an anticaking agent in animal feed, in paper making to minimize deposit formation, as a retention and drainage aid component. Montmorillonite has been used in cosmetics. In a fine powder form, it can be used as a flocculant in ponds. Tossed on the surface as it drops into the water, making the water "clouded", it attracts minute particles in the water and settles to the bottom, cleaning the water. Koi and goldfish actually feed on the "clump" which can aid in the digestion of the fish, it is sold in pond supply shops. Sodium montmorillonite is used as the base of some cat litter products, due to its adsorbent and clumping properties. Montmorillonite can be calcined to produce a porous material; this calcined clay is sold as a soil conditioner for playing fields and other soil products such as for use as bonsai soil as an alternative to akadama.
Montmorillonite is effective as an adsorptive of heavy metals. For external use, montmorillonite has been used to treat contact dermatitis. Montmorillonite clay is added to some dog and cat foods as an anti-caking agent and because it may provide some resistance to environmental toxins, though research on the subject is not yet conclusive. Montmorillonite was first described in 1847 for an occurrence in Montmorillon in the department of Vienne, more than 50 years before the discovery of bentonite in the US, it is known by other names. Montmorillonite is known to cause micelles to assemble together into vesicles; these structures resemble cell membranes on many cells. It can help nucleotides to assemble into RNA which will end up inside the vesicles; this could have generated complex RNA polymers that could reproduce the RNA trapped within the vesicles. This process may have played a part in abiogenesis. Minerals similar to montmorillonites have been found on Mars. Abiogenesis Dispersion Emulsion dispersion Sodification