1.
Microporous material
–
A microporous material is a material containing pores with diameters less than 2 nm. Examples of microporous materials include zeolites and metal-organic frameworks, porous materials are classified into several kinds by their size. Micropores may be defined differently in other contexts, for example, in the context of porous aggregations such as soil, micropores are defined as cavities with sizes less than 30 μm. Microporous materials are used in laboratory environments to facilitate contaminant-free exchange of gases. Mold spores, bacteria, and other airborne contaminants will become trapped and this allows for a sterile environment in the contained area. Microporous adhesive tape is a surgical tape used to hold wound dressings and bandages in place and it can be used to hold gauze padding over small wounds, usually as a temporary measure until a suitable dressing is applied. The Steri-Strip was derived from Microporous surgical tape, Microporous tape is used by some professional extreme yo-yoers to wrap around their fingers and prevent string burn or irritation. Rock climbers use tape to wrap their hands in tape gloves. Microporous media used in large format printing applications normally with a pigment based ink to maintain colour balance, Microporous tape is also used by some film and TV sound recordists to affix small radio microphones to actors skin. Microporous material is used as high performance insulation material used from home applications up to metal furnaces requiring material that can withstand more than 1000 Celsius. Characterisation of pore space in soil Nanoporous materials Steri strip Dressing Conjugated microporous polymer, a type of microporous material
Microporous material
–
Albupore microporous surgical tape
2.
Aluminosilicate
–
Aluminosilicate minerals are minerals composed of aluminium, silicon, and oxygen, plus countercations. They are a component of kaolin and other clay minerals. Andalusite, kyanite, and sillimanite are naturally occurring minerals that have the composition Al2SiO5. The triple point of the three polymorphs is located at a temperature of 500 °C and a pressure of 0.4 GPa and these three minerals are commonly used as index minerals in metamorphic rocks. Hydrated aluminosilicate minerals are referred to as zeolites and are porous structures that are naturally occurring materials, the catalyst silica-alumina is an amorphous substance which is not an aluminosilicate compound. There exist a variety of glass types. The characteristics of different types depend on the chemical composition of the glass with a special focus on the oxide composition. Glasses can be categorized into different groups, one of them including the so-called aluminosilicate glasses. This glass type can be differentiated, Characteristically, these glasses are free of alkali oxides and contain 15-25% AI2O3, 52-60% SiO2. Very high transformation temperatures and softening points are typical features, main fields of application are glass bulbs for halogen lamps, high-temperature thermometers and thermally and electrically highly loadable film resistors. The AI2O3 content of alkali aluminosilicate glasses is typically 10-25% and the content over 10%. The high alkali content prepares the glass for ion exchange with bigger alkali ions in order to improve the surface compressive strength, due to this particular feature, this glass type is especially suitable for the use in touch displays, solar cells cover glass and laminated safety glass. High transformation temperatures and outstanding properties, e. g. hardness. Aluminium silicate Silicate minerals Calcium aluminosilicate Sodium aluminosilicate
Aluminosilicate
–
Kyanite
3.
Mineral
–
A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin. A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids, the study of minerals is called mineralogy. There are over 5,300 known mineral species, over 5,070 of these have been approved by the International Mineralogical Association, the silicate minerals compose over 90% of the Earths crust. The diversity and abundance of species is controlled by the Earths chemistry. Silicon and oxygen constitute approximately 75% of the Earths crust, which translates directly into the predominance of silicate minerals, minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species, changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals. Minerals can be described by their various properties, which are related to their chemical structure. Common distinguishing characteristics include crystal structure and habit, hardness, lustre, diaphaneity, colour, streak, tenacity, cleavage, fracture, parting, more specific tests for describing minerals include magnetism, taste or smell, radioactivity and reaction to acid. Minerals are classified by key chemical constituents, the two dominant systems are the Dana classification and the Strunz classification, the silicate class of minerals is subdivided into six subclasses by the degree of polymerization in the chemical structure. All silicate minerals have a unit of a 4− silica tetrahedron—that is, a silicon cation coordinated by four oxygen anions. These tetrahedra can be polymerized to give the subclasses, orthosilicates, disilicates, cyclosilicates, inosilicates, phyllosilicates, other important mineral groups include the native elements, sulfides, oxides, halides, carbonates, sulfates, and phosphates. The first criterion means that a mineral has to form by a natural process, stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C, modern advances have included extensive study of liquid crystals, which also extensively involve mineralogy. Minerals are chemical compounds, and as such they can be described by fixed or a variable formula, many mineral groups and species are composed of a solid solution, pure substances are not usually found because of contamination or chemical substitution. Finally, the requirement of an ordered atomic arrangement is usually synonymous with crystallinity, however, crystals are also periodic, an ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form, hardness, and cleavage. There have been recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of an approved by the IMA in 1995, A mineral is an element or chemical compound that is normally crystalline. However, if geological processes were involved in the genesis of the compound, Mineral classification schemes and their definitions are evolving to match recent advances in mineral science
Mineral
–
Amethyst, a variety of
quartz
Mineral
–
Schist is a
metamorphic rock characterized by an abundance of platy minerals. In this example, the rock has prominent
sillimanite porphyroblasts as large as 3 cm (1.2 in).
Mineral
–
Hübnerite, the manganese-rich end-member of the
wolframite series, with minor quartz in the background
Mineral
–
When minerals react, the products will sometimes assume the shape of the reagent; the product mineral is termed to be a pseudomorph of (or after) the reagent. Illustrated here is a pseudomorph of
kaolinite after
orthoclase. Here, the pseudomorph preserved the Carlsbad
twinning common in orthoclase.
4.
Adsorption
–
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent and this process differs from absorption, in which a fluid is dissolved by or permeates a liquid or solid, respectively. Adsorption is a process while absorption involves the whole volume of the material. The term sorption encompasses both processes, while desorption is the reverse of it, similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the requirements of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms, the exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption or chemisorption. It may also occur due to electrostatic attraction, pharmaceutical industry applications, which use adsorption as a means to prolong neurological exposure to specific drugs or parts thereof, are lesser known. The word adsorption was coined in 1881 by German physicist Heinrich Kayser, adsorption is usually described through isotherms, that is, the amount of adsorbate on the adsorbent as a function of its pressure or concentration at constant temperature. The quantity adsorbed is nearly always normalized by the mass of the adsorbent to allow comparison of different materials, to date,15 different isothem models were developed. The function is not adequate at very high pressure because in reality x / m has a maximum as pressure increases without bound. As the temperature increases, the k and n change to reflect the empirical observation that the quantity adsorbed rises more slowly. Irving Langmuir was the first to derive a scientifically based adsorption isotherm in 1918, the model applies to gases adsorbed on solid surfaces. It is a semi-empirical isotherm with a basis and was derived based on statistical thermodynamics. It is the most common isotherm equation to use due to its simplicity and it is based on four assumptions, All of the adsorption sites are equivalent and each site can only accommodate one molecule. The surface is energetically homogeneous and adsorbed molecules do not interact, at the maximum adsorption, only a monolayer is formed. Adsorption only occurs on localized sites on the surface, not with other adsorbates, the fourth condition is the most troublesome, as frequently more molecules will adsorb to the monolayer, this problem is addressed by the BET isotherm for relatively flat surfaces. The Langmuir isotherm is nonetheless the first choice for most models of adsorption, Langmuir suggested that adsorption takes place through this mechanism, A g + S ⇌ A S, where A is a gas molecule and S is an adsorption site. The direct and inverse rate constants are k and k−1, vmon is related to the number of adsorption sites through the ideal gas law
Adsorption
–
Langmuir isotherm (red) and BET isotherm (green)
Adsorption
–
Two adsorbate nitrogen molecules adsorbing onto a tungsten adsorbent from the precursor state around an island of previously adsorbed adsorbate (left) and via random adsorption (right)
Adsorption
–
Activated carbon is used as an adsorbent
Adsorption
–
Silica gel adsorber for NO 2, Fixed Nitrogen Research Laboratory, ca.1930s
5.
Catalysis
–
Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst. In most cases, reactions occur faster with a catalyst because they require less activation energy, furthermore, since they are not consumed in the catalyzed reaction, catalysts can continue to act repeatedly. Often only tiny amounts are required in principle, in the presence of a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change. A catalyst may participate in multiple chemical transformations, the effect of a catalyst may vary due to the presence of other substances known as inhibitors or poisons or promoters. Catalyzed reactions have an activation energy than the corresponding uncatalyzed reaction, resulting in a higher reaction rate at the same temperature. However, the mechanics of catalysis is complex. Usually, the catalyst participates in this slowest step, and rates are limited by amount of catalyst, in heterogeneous catalysis, the diffusion of reagents to the surface and diffusion of products from the surface can be rate determining. A nanomaterial-based catalyst is an example of a heterogeneous catalyst, analogous events associated with substrate binding and product dissociation apply to homogeneous catalysts. Although catalysts are not consumed by the reaction itself, they may be inhibited, deactivated, in heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a system or sublimate in a solid–gas system. The production of most industrially important chemicals involves catalysis, similarly, most biochemically significant processes are catalysed. Research into catalysis is a field in applied science and involves many areas of chemistry, notably organometallic chemistry. Catalysis is relevant to aspects of environmental science, e. g. the catalytic converter in automobiles. Many transition metals and transition metal complexes are used in catalysis as well, Catalysts called enzymes are important in biology. A catalyst works by providing a reaction pathway to the reaction product. The rate of the reaction is increased as this route has a lower activation energy than the reaction route not mediated by the catalyst. The disproportionation of hydrogen peroxide creates water and oxygen, as shown below,2 H2O2 →2 H2O + O2 This reaction is preferable in the sense that the reaction products are more stable than the starting material, though the uncatalysed reaction is slow. In fact, the decomposition of hydrogen peroxide is so slow that hydrogen peroxide solutions are commercially available and this reaction is strongly affected by catalysts such as manganese dioxide, or the enzyme peroxidase in organisms
Catalysis
–
An
air filter that utilizes low-temperature oxidation catalyst used to convert
carbon monoxide to less toxic
carbon dioxide at room temperature. It can also remove
formaldehyde from the
air.
Catalysis
–
Zeolites are extruded as pellets for easy handling in catalytic reactors.
6.
Sweden
–
Sweden, officially the Kingdom of Sweden, is a Scandinavian country in Northern Europe. It borders Norway to the west and Finland to the east, at 450,295 square kilometres, Sweden is the third-largest country in the European Union by area, with a total population of 10.0 million. Sweden consequently has a low density of 22 inhabitants per square kilometre. Approximately 85% of the lives in urban areas. Germanic peoples have inhabited Sweden since prehistoric times, emerging into history as the Geats/Götar and Swedes/Svear, Southern Sweden is predominantly agricultural, while the north is heavily forested. Sweden is part of the area of Fennoscandia. The climate is in very mild for its northerly latitude due to significant maritime influence. Today, Sweden is a monarchy and parliamentary democracy, with a monarch as head of state. The capital city is Stockholm, which is also the most populous city in the country, legislative power is vested in the 349-member unicameral Riksdag. Executive power is exercised by the government chaired by the prime minister, Sweden is a unitary state, currently divided into 21 counties and 290 municipalities. Sweden emerged as an independent and unified country during the Middle Ages, in the 17th century, it expanded its territories to form the Swedish Empire, which became one of the great powers of Europe until the early 18th century. Swedish territories outside the Scandinavian Peninsula were gradually lost during the 18th and 19th centuries, the last war in which Sweden was directly involved was in 1814, when Norway was militarily forced into personal union. Since then, Sweden has been at peace, maintaining a policy of neutrality in foreign affairs. The union with Norway was peacefully dissolved in 1905, leading to Swedens current borders, though Sweden was formally neutral through both world wars, Sweden engaged in humanitarian efforts, such as taking in refugees from German-occupied Europe. After the end of the Cold War, Sweden joined the European Union on 1 January 1995 and it is also a member of the United Nations, the Nordic Council, Council of Europe, the World Trade Organization and the Organisation for Economic Co-operation and Development. Sweden maintains a Nordic social welfare system that provides health care. The modern name Sweden is derived through back-formation from Old English Swēoþēod and this word is derived from Sweon/Sweonas. The Swedish name Sverige literally means Realm of the Swedes, excluding the Geats in Götaland, the etymology of Swedes, and thus Sweden, is generally not agreed upon but may derive from Proto-Germanic Swihoniz meaning ones own, referring to ones own Germanic tribe
Sweden
–
A
Vendel-era helmet, at the Swedish Museum of National Antiquities.
Sweden
–
Flag
Sweden
–
A
romantic nationalist interpretation of
Valdemar IV taking control over
Gotland. The final battle outside the walls of Visby in 1361 ended with a massacre of 1,800 defenders of the city.
Sweden
–
Stockholm in mid-17th century
7.
Mineralogy
–
Mineralogy is a subject of geology specializing in the scientific study of chemistry, crystal structure, and physical properties of minerals and mineralized artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, the German Renaissance specialist Georgius Agricola wrote works such as De re metallica and De Natura Fossilium which began the scientific approach to the subject. Systematic scientific studies of minerals and rocks developed in post-Renaissance Europe, the modern study of mineralogy was founded on the principles of crystallography and to the microscopic study of rock sections with the invention of the microscope in the 17th century. Nicholas Steno first observed the law of constancy of interfacial angles in quartz crystals in 1669 and this was later generalized and established experimentally by Jean-Baptiste L. Romé de lIslee in 1783. In 1814, Jöns Jacob Berzelius introduced a classification of minerals based on their chemistry rather than their crystal structure, james D. Dana published his first edition of A System of Mineralogy in 1837, and in a later edition introduced a chemical classification that is still the standard. It, however, retains a focus on the structures commonly encountered in rock-forming minerals. An initial step in identifying a mineral is to examine its physical properties and these can be classified into density, measures of mechanical cohesion, macroscopic visual properties, magnetic and electric properties, radioactivity and solubility in hydrogen chloride. If the mineral is crystallized, it will also have a distinctive crystal habit that reflects the crystal structure or internal arrangement of atoms. It is also affected by crystal defects and twinning. Many crystals are polymorphic, having more than one crystal structure depending on factors such as pressure and temperature. ”Examples of polymorphs are calcite and aragonite - two minerals with identical chemical composition, distinguished by their crystallography, calcite is rhombohedral and aragonite is orthorhombic. The crystal structure is the arrangement of atoms in a crystal and it is represented by a lattice of points which repeats a basic pattern, called a unit cell, in three dimensions. The lattice can be characterized by its symmetries and by the dimensions of the unit cell and these dimensions are represented by three Miller indices. The lattice remains unchanged by certain symmetry operations about any point in the lattice, reflection, rotation, inversion, and rotary inversion. Together, they make up an object called a crystallographic point group or crystal class. There are 32 possible crystal classes, in addition, there are operations that displace all the points, translation, screw axis, and glide plane. In combination with the point symmetries, they form 230 possible space groups, most geology departments have X-ray powder diffraction equipment to analyze the crystal structures of minerals. X-rays have wavelengths that are the order of magnitude as the distances between atoms. In a sample that is ground to a powder, the X-rays sample a random distribution of all crystal orientations, powder diffraction can distinguish between minerals that may appear the same in a hand sample, for example quartz and its polymorphs tridymite and cristobalite
Mineralogy
–
Page from Treatise on mineralogy by
Friedrich Mohs (1825).
Mineralogy
–
Mineralogy is a mixture of
chemistry,
materials science,
physics and
geology.
Mineralogy
–
Left side of the
Moon Mineralogy Mapper, a
spectrometer that mapped the lunar surface.
Mineralogy
–
The
perovskite crystal structure. The most abundant mineral in the Earth,
bridgmanite, has this structure. Its chemical formula is (Mg,Fe)SiO 3; the red spheres are oxygen, the blue spheres silicon and the green spheres magnesium or iron.
8.
Axel Fredrik Cronstedt
–
Baron Axel Fredrik Cronstedt was a Swedish mineralogist and chemist who discovered nickel in 1751 as a mining expert with the Bureau of Mines. This name arises because the ore has an appearance to copper. Cronstedt named it nickel in 1754 and he was a pupil of Georg Brandt, the discoverer of cobalt. Cronstedt is one of the founders of modern mineralogy and is described as the founder by John Griffin in his 1827 A Practical Treatise on the Use of the Blowpipe and he remains to this day to be an outstanding idol for young swedes. Cronstedt also discovered the mineral scheelite in 1751 and he named the mineral tungsten, meaning heavy stone in Swedish. Carl Wilhelm Scheele later suggested that a new metal could be extracted from the mineral, in English, this metal is now known as the element tungsten. In 1753, Cronstedt was elected a member of the Royal Swedish Academy of Sciences, in 1756, Cronstedt coined the term zeolite after heating the mineral stilbite with a blowpipe flame. Gusenius, E M. Beginnings of greatness in Swedish Chemistry, a Practical Treatise on the Use of the Blowpipe by John Griffin,1827, from Google Book Search
Axel Fredrik Cronstedt
–
Axel Fredrik Cronstedt
9.
Stilbite
–
Stilbite is the name of a series of tectosilicate minerals of the zeolite group. In the case of stilbite-Na, sodium dominates over calcium, the species are visually indistinguishable, and the series name stilbite is still used whenever testing has not been performed. At one time heulandite and stilbite were considered to be identical minerals, after they were found to be two separate species, in 1818, the name desmine was proposed for stilbite, and this name is still employed in Germany. The English name stilbite is from the Greek stilbein = to shine, stilbite shows a wide variation in exchangeable cations, silicon and aluminium ions occupy equivalent sites and can substitute for each other. Since silicon and aluminium have a different charge the ions occupying the site have to adjust to maintain charge balance. There is a series between stellerite, whose formula can be written as Ca4O72·28, and stilbite, and another continuous series between stilbite and barrerite, Na8O72·26. Epistilbite is a distinct zeolite species unrelated to stilbite, stilbite is usually monoclinic 2/m, meaning that it has one twofold axis of rotational symmetry perpendicular to a mirror plane. The twofold axis is the crystal axis b, and the a and c axes lie in the mirror plane. For a monoclinic crystal a and c are inclined to each other at an angle β which is not a right angle, for stilbite β is nearly 130°. The mineral is said to be pseudo-orthorhombic, non-endmember forms of stilbite may be triclinic or even truly orthorhombic, indeed the framework can have symmetry ranging from orthorhombic to triclinic in a single crystal. Crystals are typically tabular, flattened parallel to the dominant cleavage. Aggregates may be sheaf-like or in bow-ties, also fibrous and globular, twinning, cruciform and penetration, is extremely common on. The color is colorless or white, also yellow, brown, pink, salmon, orange, red, green. The luster is vitreous, and on the perfect cleavage parallel to the plane of symmetry it is markedly pearly. The streak is white and crystals are transparent to translucent, the hardness is 3½ to 4 and the specific gravity 2.12 to 2.22. Cleavage is perfect on, poor on, the mineral is brittle, with a conchoidal or uneven fracture. The unit cell can be considered as a cell with β close to 130° and one formula unit per unit cell, or as a larger pseudo-orthorhombic cell with β close to 90°. It has 10-member rings and 8-member rings forming channels parallel to a, the open channels in the stilbite structure act like a molecular sieve, enabling it to separate hydrocarbons in the process of petroleum refining
Stilbite
–
Stilbite from Kiui Island, Alaska, USA
Stilbite
–
Intergrown, doubly terminated stilbite crystals from the Pune District of India.
Stilbite
–
Intergrown pinkish stilbite crystals showing the "bow-tie" habit from Jalgaon District, Maharashtra, India.
Stilbite
–
Stilbite crystals aggregates in fans shapes from Wassons Bluff, Nova Scotia.
10.
Greek language
–
Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
Greek language
–
Idealized portrayal of
Homer
Greek language
–
regions where Greek is the official language
Greek language
–
Greek language road sign, A27 Motorway, Greece
11.
Thomsonite
–
Thomsonite is the name of a series of tecto-silicate minerals of the zeolite group. Thomsonite-Ca, by far the more common of the two is a sodium, calcium and aluminium silicate, NaCa2Al5Si5O20·6H2O. Strontium can substitute for the calcium and the species name depends on the dominant element. The species are visually indistinguishable and the series name thomsonite is used whenever testing has not been performed, globally, thomsonite is one of the rarer zeolites. Thomsonite was first identified in material from Scotland in 1820 and it is named for the Scottish chemist Thomas Thomson. The crystal system of thomsonite is orthorhombic, the Mohs hardness is 5 to 5.5. It is transparent to translucent and has a density of 2.3 to 2.4 and it may be colorless, white, beige, or somewhat green, yellow, or red. The crystals tend to be long thin blades that typically form radial aggregates, the aggregates are variable and may be spikey in appearance, dense and ball-like, or form worm-like growths. Tight acicular radiating clusters and sphericules are common forms, Thomsonite occurs with other zeolites in the amygdaloidal cavities of basaltic volcanic rocks, and occasionally in granitic pegmatites. Examples have been found in Faroe Islands, Scotland, Arkansas, Colorado, Michigan, Minnesota, New Jersey, Oregon, Ontario, Nova Scotia, India, nodules of massive thomsonite that display an attractive banded coloring are found along the shore of Lake Superior. Most of these nodules and their derived pebbles are less than 0.6 cm. Those enclosed in basalt are extremely difficult to remove without breaking them, consequently, a very large percentage of those used as gemstones are from pebbles collected from beaches. Mindat Thomsonite-Ca Webmineral Thomsonite-Ca IMA Zeolite Classification R. V. Dietrich, Thomsonite Structure type THO
Thomsonite
–
Thomsonite from
Minnesota
12.
Cations
–
An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges, cations and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion, going and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday also introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions. Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge. A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
Cations
13.
Analcime
–
Analcime or analcite is a white, gray, or colorless tectosilicate mineral. Analcime consists of hydrated sodium aluminium silicate in cubic crystalline form, minor amounts of potassium and calcium substitute for sodium. A silver-bearing synthetic variety also exists, analcime is usually classified as a zeolite mineral, but structurally and chemically it is more similar to the feldspathoids. Analcime occurs as a mineral in analcime basalt and other alkaline igneous rocks. It also occurs as cavity and vesicle fillings associated with prehnite, calcite, list of minerals Hurlbut, Cornelius S. Klein, Cornelis,1985, Manual of Mineralogy, 20th ed. ISBN 0-471-80580-7 Mineral Galleries Mindat. org Webmineral. com structure type ANA
Analcime
–
Analcime with
aegirine and
natrolite from Mont Saint-Hilaire,
Québec (size: 78 x 65 x 53 mm)
14.
Chabazite
–
Chabazite is a tectosilicate mineral of the zeolite group, closely related to gmelinite, with formula Al2Si4O12·6H2O. Recognized varieties include Chabazite-Ca, Chabazite-K, Chabazite-Na, and Chabazite-Sr, chabazite crystallizes in the triclinic crystal system with typically rhombohedral shaped crystals that are pseudo-cubic. The crystals are twinned, and both contact twinning and penetration twinning may be observed. They may be colorless, white, orange, brown, pink, green, the hardness ranges from 3 to 5 and the specific gravity from 2.0 to 2.2. It was named chabasie in 1792 by Bosc dAntic and later changed to the current spelling, chabazite occurs most commonly in voids and amygdules in basaltic rocks. Chabazite is found in India, Iceland, the Faroe Islands, the Giants Causeway in Northern Ireland, Bohemia, Italy, Germany, along the Bay of Fundy in Nova Scotia, Oregon, Arizona, many different materials isostructural with the chabazite mineral have been synthesized in laboratories. SSZ-13 is a CHA type zeolite with an Si/Al ratio of 14 and this is a composition not found in nature. Webmineral Mineral Galleries mindat. org structure type CHA
Chabazite
–
Orange chabazite rhombs with white heulandite from Nova Scotia
15.
Clinoptilolite
–
Clinoptilolite is a natural zeolite comprising a microporous arrangement of silica and alumina tetrahedra. It has the formula, 2-3Al32Si13O36·12H2O. It forms as white to reddish tabular monoclinic tectosilicate crystals with a Mohs hardness of 3.5 to 4 and it commonly occurs as a devitrification product of volcanic glass shards in tuff and as vesicle fillings in basalts, andesites and rhyolites. It was described in 1969 from an occurrence in Owl Canyon, San Bernardino County, a typical example of this is in its use as an enzyme-based urea sensor. It is also used as fertiliser and sold as a deodorizer in the form of pebble-sized chunks contained in a mesh bag, research is generally focussed around the shores of the Aegean Sea due to the abundance of natural clinoptilolite in easily accessible surface deposits. The name is derived from the Greek words klino, ptylon, paulingite Mineral galleries Webmineral data Mindat with location data
Clinoptilolite
–
Clinoptilolite-Na
16.
Heulandite
–
Heulandite is the name of a series of tecto-silicate minerals of the zeolite group. Heulandite-Ca, the most common of these, is a calcium and aluminium silicate. Small amounts of sodium and potassium are usually present replacing part of the calcium, strontium replaces calcium in the heulandite-Sr variety. The appropriate species name depends on the dominant element, the species are visually indistinguishable, and the series name heulandite is still used whenever testing has not been performed. They may have a characteristic coffin-shaped habit, but may form simple rhombic prisms. Frequently, a crust of fine crystals will form only the ends of the rhombs visible. They have a perfect parallel to the plane of symmetry, on which the lustre is markedly pearly. The mineral is colourless or white, but may be orange, brown, yellow, brick-red. It varies from transparent to translucent, isomorphous with heulandite is the strontium and barium zeolite brewsterite. The Mohs hardness is 3-4, and the specific gravity 2.2, the two minerals may, however, be readily distinguished by the fact that in heulandite the acute positive bisectrix of the optic axes emerges perpendicular to the cleavage. Heulandite occurs with stilbite and other zeolites in the cavities of basaltic volcanic rocks. Good specimens have been found in the basalts of Berufjörður, near Djúpivogur, in Iceland, the Faroe Islands, crystals of a brick-red colour are from Campsie Fells in Stirlingshire and the Fassa valley in Trentino. A variety known as beaumontite occurs as yellow crystals on syenitic schist near Baltimore. Mineral Galleries IMA Zeolite Classification Attribution This article incorporates text from a now in the public domain, Spencer
Heulandite
–
Heulandite, Lonavala Quarry,
Pune District,
Maharashtra, India. Size of individual crystals: 3-5cm.
Heulandite
–
Heulandite, Berufjördur,
Suður-Múlasýsla,
Iceland. Clusters of pearlescent, curved heulandite crystals cover the vuggy, thin basalt matrix. Heulandite crystals are up to 2 cm.
17.
Natrolite
–
Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na2Al2Si3O10 · 2H2O, the type locality is Hohentwiel, Hegau, Germany. It was named natrolite by Martin Heinrich Klaproth in 1803, the name is derived from νατρών natron, the Greek word for soda, in reference to the sodium content and λίθος lithos, meaning stone. Needle stone or needle-zeolite are other names, alluding to the common acicular habit of the crystals. The crystals are frequently epitaxial overgrowths of natrolite, mesolite, larger crystals most commonly have the form of a square prism terminated by a low pyramid, the prism angle being nearly a right angle. The crystals are tetragonal in appearance, though actually orthorhombic, there are perfect cleavages parallel to the faces of the prism. The mineral also occurs in compact fibrous aggregates, the fibers having a divergent or radial arrangement. Natrolite is readily distinguished from other fibrous zeolites by its optical characteristics, between crossed nicols the fibers extinguish parallel to their length, and they do not show an optic figure in convergent polarized light. Natrolite is usually white or colorless, but sometimes reddish or yellowish, the luster is vitreous, or, in finely fibrous specimens, silky. The specific gravity is 2.2, and the hardness is 5.5, the mineral is readily fusible, melting in a candle-flame to which it imparts a yellow color owing to the presence of sodium. It is decomposed by hydrochloric acid with separation of gelatinous silica, natrolite occurs with other zeolites in the amygdaloidal cavities of basaltic igneous rocks. It is also common in nepheline syenites, excellent specimens of diverging groups of white prismatic crystals are found in compact basalt at the Puy-deMarman, Puy-de-Dôme, France. Huge crystals have found on the Kola Peninsula, Russia. Mont St. Hilaire, Quebec has produced large crystals associated with many rare minerals, the Bay of Fundy in Nova Scotia, New Jersey, Oregon, and British Columbia have also produced excellent specimens. Several varieties of natrolite have been distinguished by special names, fargite is a red natrolite from Glenfarg in Perthshire. Bergmannite, or Spreustein, is a variety which has resulted by the alteration of other minerals, chiefly sodalite. Structure type NAT Mineral Galleries Mindat Webmineral This article incorporates text from a now in the public domain, Chisholm, Hugh
Natrolite
–
Natrolite
18.
Phillipsite
–
Phillipsite is a mineral series of the zeolite group, a hydrated potassium, calcium and aluminium silicate, approximating to 3Al6Si10O32·12H2O. The members of the series are phillipsite-K, phillipsite-Na and phillipsite-Ca, the crystals are monoclinic, but only complex cruciform twins are known, these being exactly like twins of harmotome which also forms a series with phillipsite-Ca. Crystals of phillipsite are, however, usually smaller and more transparent, spherical groups with a radially fibrous structure and bristled with crystals on the surface are not uncommon. The Mohs hardness is 4.5, and the gravity is 2.2. The species was established by Armand Lévy in 1825 and named after William Phillips, french authors use the name Christianite, given by A. Small crystals of recent formation have been observed in the masonry of the hot baths at Plombires and Bourbonne-les-Bains, minute spherical aggregates embedded in pelagic red clay were dredged by the Challenger from deep sea sedimenary deposits in the Pacific Ocean. List of minerals List of minerals named after people Leonard James Spencer
Phillipsite
–
Phillipsite from Tasmania
19.
Volcanic
–
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, therefore, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateaus
Volcanic
–
Cleveland Volcano in the
Aleutian Islands of
Alaska photographed from the
International Space Station, May 2006
Volcanic
–
Ash plumes reached a height of 19 kilometres (12 mi) during the climactic
explosive eruption at
Mount Pinatubo, Philippines in 1991.
Volcanic
–
A 2007 eruptive column at
Mount Etna producing volcanic ash, pumice and lava bombs
Volcanic
–
Ubinas Volcano
20.
Volcanic ash
–
Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions and measuring less than 2 mm in diameter. The term volcanic ash is often loosely used to refer to all explosive eruption products. Volcanic ash is formed during volcanic eruptions when dissolved gases in magma expand. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, once in the air, ash is transported by wind up to thousands of kilometers away. Volcanic ash is formed during volcanic eruptions, phreatomagmatic eruptions. Explosive eruptions occur when magma decompresses as it rises, allowing dissolved volatiles to exsolve into gas bubbles, as more bubbles nucleate a foam is produced, which decreases the density of the magma, accelerating it up the conduit. Fragmentation occurs when bubbles occupy ~70-80 vol% of the erupting mixture, when fragmentation occurs, violently expanding bubbles tear the magma apart into fragments which are ejected into the atmosphere where they solidify into ash particles. Fragmentation is an efficient process of ash formation and is capable of generating very fine ash even without the addition of water. Volcanic ash is produced during phreatomagmatic eruptions. During these eruptions fragmentation occurs when magma comes into contact with bodies of water groundwater, as the magma, which is significantly hotter than the boiling point of water, comes into contact with water an insulating vapor film forms. Eventually this vapor film will collapse leading to direct coupling of the cold water and this increases the heat transfer which leads to the rapid expansion of water and fragmentation of the magma into small particles which are subsequently ejected from the volcanic vent. Fragmentation causes an increase in area between magma and water creating a feedback mechanism, leading to further fragmentation and production of fine ash particles. Pyroclastic density currents can also produce ash particles and these are typically produced by lava dome collapse or collapse of the eruption column. Within pyroclastic density currents particle abrasion occurs as particles interact with each resulting in a reduction in grain size. In addition, ash can be produced during secondary fragmentation of pumice fragments and these processes produce large quantities of very fine grained ash which is removed from pyroclastic density currents in co-ignimbrite ash plumes. Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption, another parameter controlling the amount of ash produced is the duration of the eruption, the longer the eruption is sustained, the more ash will be produced. The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it erupted, low energy eruptions of basalt produce a characteristically dark coloured ash containing ~45 - 55% silica that is generally rich in iron and magnesium
Volcanic ash
–
Ash cloud from the 2008 eruption of
Chaitén volcano,
Chile, stretching across
Patagonia from the
Pacific to the
Atlantic Ocean.
Volcanic ash
–
Ash plume from
Mt Cleveland, a
stratovolcano.
Volcanic ash
–
454 million year old volcanic ash between layers of
limestone in the catacombs of
Peter the Great's Naval Fortress in
Estonia near
Laagri. The diameter of objective cover is 58 mm (2.3 in). This is remnant of one of the oldest
large eruptions preserved.
Volcanic ash
–
Particle of volcanic ash from
Mount St. Helens.
21.
Alkaline
–
Alkalinity is the name given to the quantitative capacity of an aqueous solution to neutralize an acid. Measuring alkalinity is important in determining a streams ability to neutralize acidic pollution from rainfall or wastewater and it is one of the best measures of the sensitivity of the stream to acid inputs. There can be changes in the alkalinity of streams and rivers in response to human disturbances. Alkalinity is related to the pH of a solution, but measures a different property, roughly, the alkalinity of a solution is a measure of how strong the bases are in a solution, whereas the pH measures the amount of chemical bases. A good example is a solution, which can have many available bases despite having only a moderate pH level. Alkalinity roughly refers to the amount of bases in a solution that can be converted to uncharged species by a strong acid. The cited author, James Drever, provides an equation expressed in terms of molar equivalents, which means the number of moles of each ion type multiplied by the charge of the ion. For example,1 mole of HCO31− in solution represents 1 molar equivalent, the total charge of a solution always equals zero. On the left-hand side of the equation is the sum of conservative cations minus the sum of conservative anions, balancing this on the right side is the sum of the anions that could be neutralized by added H+ ions minus H+ ions already present, as indicated by the pH. This right side term is called total alkalinity and it is, quoting Drever, formally defined as the equivalent sum of the bases that are titratable with strong acid. The listing of ions shown on the right in Drever was mHCO3− + 2mCO32− + mB4− + mH34− + mHS− + morganic anions + mOH− - mH+, total alkalinity is measured by adding a strong acid until all the anions listed above are converted to uncharged species. The total alkalinity is not affected by temperature, pressure, or pH, though the values of individual constituents are, Drever further notes that in most natural waters, all ions except HCO3− and CO3−2 have low concentrations. Thus carbonate alkalinity, which is equal to mHCO3− + 2mCO3−2 is also equal to the total alkalinity. Alkalinity or AT measures the ability of a solution to neutralize acids to the point of carbonate or bicarbonate. The alkalinity is equal to the sum of the bases in solution. Other common natural components that can contribute to alkalinity include borate, hydroxide, phosphate, silicate, dissolved ammonia, the bases of some organic acids. Solutions produced in a laboratory may contain a virtually limitless number of bases that contribute to alkalinity, Alkalinity is usually given in the unit mEq/L. Commercially, as in the pool industry, alkalinity might also be given in parts per million of equivalent calcium carbonate
Alkaline
–
Sea surface alkalinity (from the
GLODAP climatology).
22.
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
23.
Molecular sieve
–
A molecular sieve is a material with pores of uniform size. These pore diameters are similar in size to small molecules, and thus large molecules cannot enter or be absorbed, some molecular sieves are used in chromatography, a separation technique that sorts molecules based on their size. Other molecular sieves are used as desiccants, the diameter of a molecular sieve is measured in ångströms or nanometres. Molecular sieves can be microporous, mesoporous, or macroporous material.7 nm, halloysite naturally occurs as small cylinders which average 30 nm in diameter with lengths between 0.5 and 10 micrometres. Silicon dioxide,24 Å Mesoporous silica, 200–1000 Å Molecular sieves are often utilized in the petroleum industry, for example, in the liquid natural gas industry, the water content of the gas needs to be reduced to less than 1 ppmv to prevent blockages caused by ice. In the laboratory, molecular sieves are used to dry solvent, Sieves have proven to be superior to traditional drying techniques, which often employ aggressive desiccants. Under the term zeolites, molecular sieves are used for a range of catalytic applications. They catalyze isomerisation, alkylation, and epoxidation, and are used in large scale industrial processes, including hydrocracking and they are also used in the filtration of air supplies for breathing apparatus, for example those used by scuba divers and firefighters. Such filtration can remove particulates and compressor exhaust products from the air supply. The U. S. FDA has as of April 1,2012 approved sodium aluminosilicate for direct contact with consumable items under 21 CFR182.2727. Methods for regeneration of molecular sieves include pressure change, heating and purging with a carrier gas, regeneration temperatures range from 175 °C to 315 °C depending on molecular sieve type. In contrast, silica gel can be regenerated by heating it in an oven to 120 °C for two hours. However, some types of silica gel will pop when exposed to enough water and this is caused by breakage of the silica spheres when contacting the water. Approximate chemical formula, 2/3K2O•1/3Na2O•Al2O3•2 SiO2 • 9/2 H2O Silica-alumina ratio, the characteristics of these molecular sieves include fast adsorption speed, frequent regeneration ability, good crushing resistance and pollution resistance. These features can improve both the efficiency and lifetime of the sieve, 3Å molecular sieves are the necessary desiccant in petroleum and chemical industries for refining oil, polymerization, and chemical gas-liquid depth drying. 3Å molecular sieves are used to dry a range of materials, such as ethanol, air, refrigerants, natural gas, the latter include cracking gas, acetylene, ethylene, propylene and butadiene. Once the beads are full of water, temperature or pressure can be manipulated, 3Å molecular sieves are stored at room temperature, with a relative humidity not more than 90%. They are sealed under reduced pressure, being away from water, acids
Molecular sieve
–
A sealed canister, commonly filled with
silica gel and other
molecular sieves used as
desiccant in drug containers to keep contents dry. The
US Quarter in the photo is 26.5 millimetres (1.04 in) in diameter.
Molecular sieve
–
Vials of
mesoporous silica
Molecular sieve
–
Bottle of 4A molecular sieves.
24.
Weathering
–
Weathering is the breaking down of rocks, soil, and minerals as well as wood and artificial materials through contact with the Earths atmosphere, waters, and biological organisms. Two important classifications of weathering processes exist – physical and chemical weathering, mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, such as heat, water, ice and pressure. While physical weathering is accentuated in very cold or very dry environments, chemical reactions are most intense where the climate is wet, however, both types of weathering occur together, and each tends to accelerate the other. For example, physical abrasion decreases the size of particles and therefore increases their surface area, the various agents act in concert to convert primary minerals to secondary minerals and release plant nutrient elements in soluble forms. The materials left over after the rock breaks down combined with organic material creates soil, in addition, many of Earths landforms and landscapes are the result of weathering processes combined with erosion and re-deposition. Physical weathering, also recognized as mechanical weathering, is the class of processes that causes the disintegration of rocks without chemical change, the primary process in physical weathering is abrasion. However, chemical and physical weathering often go hand in hand, physical weathering can occur due to temperature, pressure, frost etc. For example, cracks exploited by physical weathering will increase the area exposed to chemical action. Abrasion by water, ice, and wind loaded with sediment can have tremendous cutting power, as is amply demonstrated by the gorges, ravines. In glacial areas, huge moving ice masses embedded with soil and rock fragments grind down rocks in their path, plant roots sometimes enter cracks in rocks and pry them apart, resulting in some disintegration, Burrowing animals may help disintegrate rock through their physical action. However, such influences are usually of importance in producing parent material when compared to the drastic physical effects of water, ice, wind. Physical weathering is called mechanical weathering or disaggregation. Thermal stress weathering results from the expansion and contraction of rock, for example, heating of rocks by sunlight or fires can cause expansion of their constituent minerals. As some minerals expand more than others, temperature changes set up differential stresses that cause the rock to crack apart. Because the outer surface of a rock is often warmer or colder than the more protected inner portions and this process may be sharply accelerated if ice forms in the surface cracks. When water freezes, it expands with a force of about 1465 Mg/m^2, disintegrating huge rock masses, thermal stress weathering comprises two main types, thermal shock and thermal fatigue. Thermal stress weathering is an important mechanism in deserts, where there is a diurnal temperature range, hot in the day. The repeated heating and cooling exerts stress on the layers of rocks
Weathering
–
A
natural arch produced by erosion of differentially weathered rock in Jebel Kharaz (
Jordan)
Weathering
–
A rock in
Abisko,
Sweden fractured along existing
joints possibly by frost weathering or thermal stress
Weathering
–
Wave action and water chemistry lead to structural failure in exposed rocks
Weathering
–
Pressure release could have caused the exfoliated granite sheets shown in the picture.
25.
Metamorphism
–
Metamorphism is the change of minerals or geologic texture in pre-existing rocks, without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids, the chemical components and crystal structures of the minerals making up the rock may change even though the rock remains a solid. Changes at or just beneath Earths surface due to weathering and/or diagenesis are not classified as metamorphism, Metamorphism typically occurs between diagenesis, and melting. Three types of metamorphism exist, contact, dynamic, and regional, Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism, Metamorphic rocks can change without melting. When pressure is applied, somewhat flattened grains that orient in the same direction have a stable configuration. The upper boundary of metamorphic conditions is related to the onset of melting processes in the rock, the maximum temperature for metamorphism is typically 700 –900 °C, depending on the pressure and on the composition of the rock. Migmatites are rocks formed at this limit, which contain pods. Since the 1980s it has recognized that rocks are rarely dry enough. Conditions producing widespread regionally metamorphosed rocks occur during an orogenic event, the collision of two continental plates or island arcs with continental plates produce the extreme compressional forces required for the metamorphic changes typical of regional metamorphism. These orogenic mountains are eroded, exposing the intensely deformed rocks typical of their cores. The conditions within the slab as it plunges toward the mantle in a subduction zone also produce regional metamorphic effects. The techniques of structural geology are used to unravel the collisional history, regional metamorphism can be described and classified into metamorphic facies or metamorphic zones of temperature/pressure conditions throughout the orogenic terrane. Contact metamorphism occurs typically around intrusive igneous rocks as a result of the increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole, contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of deformation and are often fine-grained. Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact, the size of the aureole depends on the heat of the intrusion, its size, and the temperature difference with the wall rocks. Dikes generally have small aureoles with minimal metamorphism whereas large ultramafic intrusions can have significantly thick, the metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole
Metamorphism
–
A metamorphic aureole in the Henry Mountains, Utah. The greyish rock on top is the igneous intrusion, consisting of porphyritic granodiorite from the
Henry Mountains laccolith, and the pinkish rock on the bottom is the sedimentary country rock, a siltstone. In between, the metamorphosed siltstone is visible as both the dark layer (~5cm thick) and the pale layer below it.
Metamorphism
–
Schematic representation of a metamorphic reaction. Abbreviations of minerals: act =
actinolite; chl =
chlorite; ep =
epidote; gt =
garnet; hbl =
hornblende; plag =
plagioclase. Two minerals represented in the figure do not participate in the reaction, they can be
quartz and
K-feldspar. This reaction takes place in nature when a rock goes from
amphibolite facies to
greenschist facies.
Metamorphism
–
Metamorphic Facies with regard to temperature and pressure
26.
Volcanic rock
–
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin, for these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term volcanic is often applied to what are strictly metavolcanic rocks, Volcanic rocks are among the most common rock types on Earths surface, particularly in the oceans. On land, they are common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earths current land surface, lava Tephra Volcanic bomb Lapilli Volcanic ash Volcanic rocks are usually fine-grained or aphanitic to glass in texture. They often contain clasts of other rocks and phenocrysts, phenocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a fine grained matrix. Volcanic rocks often have a vesicular texture caused by voids left by volatiles trapped in the molten lava, pumice is a highly vesicular rock produced in explosive volcanic eruptions. Most modern petrologists classify igneous rocks, including rocks, by their chemistry when dealing with their origin. The fact that different mineralogies and textures may be developed from the same initial magmas has led petrologists to rely heavily on chemistry to look at a volcanic rocks origin. The chemistry of volcanic rocks is dependent on two things, the composition of the primary magma and the subsequent differentiation. Differentiation of most volcanic rocks tends to increase the silica content, the initial composition of most volcanic rocks is basaltic, albeit small differences in initial compositions may result in multiple differentiation series. The most common of these series are tholeiitic, calc-alkaline, most volcanic rocks share a number of common minerals. Differentiation of volcanic rocks tends to increase the silica content mainly by fractional crystallization, thus, more evolved volcanic rocks tend to be richer in minerals with a higher amount if silica such as phyllo and tectosilicates including the feldspars, quartz polymorphs and muscovite. While still dominated by silicates, more volcanic rocks have mineral assemblages with less silica, such as olivine. Bowens reaction series correctly predicts the order of formation of the most common minerals in volcanic rocks, occasionally, a magma may pick up crystals that crystallized from another magma, these crystals are called xenocrysts. Diamonds found in kimberlites are rare but well-known xenocrysts, the kimberlites do not create the diamonds, Volcanic rocks are named according to both their chemical composition and texture. Basalt is a common volcanic rock with low silica content
Volcanic rock
–
Ignimbrite is a deposit of a
pyroclastic flow.
Volcanic rock
–
Photomicrograph of a
volcanic lithic fragment (
sand grain); upper picture is plane-polarized light, bottom picture is cross-polarized light, scale box at left-center is 0.25 millimeter.
Volcanic rock
–
Vesicular olivine basalt from
La Palma (green phenocrysts are
olivine).
Volcanic rock
–
ʻAʻā next to pāhoehoe lava at the
Craters of the Moon National Monument and Preserve, Idaho, United States.
27.
Clay
–
Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to water content and become hard, brittle. Depending on the content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size, silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in size and other physical properties. The distinction between silt and clay varies by discipline, geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm, sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils Atterberg limits, ISO14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. These solvents, usually acidic, migrate through the rock after leaching through upper weathered layers. In addition to the process, some clay minerals are formed through hydrothermal activity. There are two types of deposits, primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation, secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with very low energy depositional environments such as large lakes. Depending on the source, there are three or four main groups of clays, kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a group within the phyllosilicates. There are approximately 30 different types of clays in these categories. Varve is clay with visible annual layers, which are formed by deposition of those layers and are marked by differences in erosion. This type of deposit is common in glacial lakes
Clay
–
Gay Head cliffs in
Martha's Vineyard consist almost entirely of clay.
Clay
–
Electron microscope photograph of smectite clay – magnification 23,500
Clay
–
Quaternary clay in
Estonia
Clay
–
Deforestation for clay extraction in
Rio de Janeiro,
Brazil. The picture is of Morro da Covanca, Jacarepaguá.
28.
Mordenite
–
Mordenite is a zeolite mineral with the chemical formula, Al2Si10O24·7H2O. According to Ullmanns Encyclopedia of Industrial Chemistry, it is one of the six most abundant zeolites and is used commercially and it was first described in 1864 by Henry How. He named it after the community of Morden, Nova Scotia, Canada, along the Bay of Fundy. It crystallizes in the form of aggregates, masses. It may be colorless, white, or faintly yellow or pink and it has Mohs hardness of 5 and a density of 2.1 g/cm3. When it forms well developed crystals they are hairlike, very long, thin, mordenite’s molecular structure is a framework containing chains of five-membered rings of linked silicate and aluminate tetrahedra. Its high ratio of silicon to aluminum atoms makes it resistant to attack by acids than most other zeolites. Mordenite is one of the most abundant zeolites in altered volcanic deposits, it is found in volcanic rock such as rhyolite, andesite and it is associated with other zeolites such as stilbite and heulandite. Good examples have found in Iceland, India, Italy, Oregon, Washington. It is also found in sediments, as in the Ural Mountains and in dikes where water has attacked and altered volcanic glasses. Synthetic Mordenite is used as a catalyst in the industry for the acid-catalyzed isomerisation of alkanes. Sedimentary deposits of mordenite are present in countries, especially in Bulgaria, Hungary, Japan. Quarried material is generally substantial, e. g. a recent estimate of the production in Japan is 150,000 tons. Apart from generic applications in the fields of agriculture and building industry, uses are known as sorbent, gas separation processes are reported for the production of high-grade O2 from air by pressure-swing operating generators. Full-scale plants based on mordenite-rich tuffs have been operating in Japan since the end of the 1960
Mordenite
–
Mordenite sprays within a
vug
Mordenite
–
Mordenite from Italy
29.
Epistilbite
–
Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts. Based on this, he called the material zeolite, from the Greek ζέω, meaning to boil and λίθος, the classic reference for the field has been Zeolite molecular sieves, structure, chemistry, and use by Donald W. Breck. Zeolites occur naturally but are produced industrially on a large scale. As of September 2016,232 unique zeolite frameworks have been identified, every new zeolite structure that is obtained has to be approved by the International Zeolite Association Structure Commission and receives a three letter designation. Zeolites have a structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+. These positive ions are rather loosely held and can readily be exchanged for others in a contact solution, some of the more common mineral zeolites are analcime, chabazite, clinoptilolite, heulandite, natrolite, phillipsite, and stilbite. An example of the formula of a zeolite is, Na2Al2Si3O10·2H2O. Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater, Zeolites also crystallize in post-depositional environments over periods ranging from thousands to millions of years in shallow marine basins. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, metals, quartz, for this reason, naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential. Zeolites are the members of the family of microporous solids known as molecular sieves mainly consisting of Si, Al, O, and metals including Ti, Sn, Zn. The term molecular sieve refers to a property of these materials. This is due to a very regular structure of molecular dimensions. The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the dimensions of the channels, therefore, the pores in many zeolites are not cylindrical. Zeolites transform to other minerals under weathering, hydrothermal alteration or metamorphic conditions, the sequence of silica-poor volcanic rocks commonly progresses from, Cowlesite → levyne–offretite → analcime → thomsonite–mesolite-scolecite → chabazite → calcite. Industrially important zeolites are produced synthetically, typical procedures entail heating aqueous solutions of alumina and silica with sodium hydroxide. Equivalent reagents include sodium aluminate and sodium silicate, further variations include changes in the cations to include quaternary ammonium cations. Synthetic zeolites hold some key advantages over their natural analogues, the synthetic materials are manufactured in a uniform, phase-pure state. It is also possible to produce zeolite structures that do not appear in nature, Zeolite A is a well-known example
Epistilbite
–
Zeolite
Epistilbite
–
A form of
thomsonite (one of the rarest zeolites) from India
Epistilbite
–
Natrolite from Poland
Epistilbite
–
Synthetic zeolite
30.
Mesolite
–
Mesolite is a tectosilicate mineral with formula Na2Ca23·8H2O. It is a member of the group and is closely related to natrolite which it also resembles in appearance. Mesolite crystallizes in the system and typically forms fibrous, acicular prismatic crystals or masses. Radiating sprays of crystals are not uncommon. It is vitreous in luster and clear to white in color and it has a Mohs hardness of 5 to 5.5 and a low specific gravity of 2.2 to 2.4. The refractive indices are nα=1.505 nβ=1.505 nγ=1.506 and it was first described in 1816 for an occurrence in the Cyclopean Islands near Catania, Sicily. From the Greek mesos, middle, as its composition lies between natrolite and scolecite, like other zeolites, mesolite occurs as void fillings in amygdaloidal basalt also in andesites and hydrothermal veins
Mesolite
–
Mesolite from the Cullen Hall of Minerals exhibit
Mesolite
–
Mesolite often forms in fibrous
crystals.
This article incorporates public domain material from the United States Geological Survey document: "Zeolites" (PDF).
This article incorporates 
. PMID 10097058. doi:10.1073/pnas.96.7.3463.
