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Margarite
Margarite is a calcium rich member of the mica group of the phyllosilicates with formula: Ca Al2(Al2 Si2) O10(O H)2. It forms white to pinkish or yellowish gray masses or thin laminae. It crystallizes in the monoclinic crystal system. It typically has a specific gravity of around 3 and a Mohs hardness of 4. It is translucent with perfect 010 cleavage and exhibits crystal twinning. It occurs commonly as an alteration product of corundum, andalusite and other aluminous minerals. It has been reported as forming alteration pseudomorphs of chiastolite along with muscovite and paragonite. The margarite in this occurrence forms preferentially along the dark graphite rich inclusions with the chiastolite crystals. Margarite is found in the emery deposits of Turkey and the Aegean islands, and with corundum at several localities in the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiastolite
Chiastolite ( ) is a variety of the mineral andalusite with the chemical composition Al2SiO5. It is noted for distinctive cross-shaped black inclusions of graphite. The presence of the cross caused this mineral be used as a gem. Chiastolite specimens were distributed throughout Europe from the 16th century, as an amulet or souvenir provided by the pilgrims returning from Santiago de Compostela (Saint James of Compostella), in Spain. In the old books of mineralogy, chiastolite appears it is cited with the name of l''apis crucifer'' or ''lapis cruciatur'', cross stone. The first figure of a chiastolite appears in Laet's book ''De Gemmis et Lapidibus'', published in 1648. The chiastolite specimens sold to the pilgrims came from Asturias, where it is very abundant, in large specimens, in the area of Boal. In areas around Georgetown, California, metamorphosed sediments contained andalusite and chiastolite in a graphite-rich metasediment. The chiastolite crystals have been pseudomorph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate Minerals
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually considered a silicate mineral. Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from seawater. The frustules of dead diatoms are a major constituent of deep ocean sediment, and of diatomaceous earth. General structure A silicate mineral is general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corundum
Corundum is a crystalline form of aluminium oxide () typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange. The name "corundum" is derived from the Tamil- Dravidian word ''kurundam'' (ruby-sapphire) (appearing in Sanskrit as ''kuruvinda''). Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. It is commonly used as an abrasive on sandpaper and on large tools used in machining metals, plastics, and wood. Emery, a variety of corundum with no value a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoclinic Minerals
In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a parallelogram prism. Hence two pairs of vectors are perpendicular (meet at right angles), while the third pair makes an angle other than 90°. Bravais lattices Two monoclinic Bravais lattices exist: the primitive monoclinic and the base-centered monoclinic. For the base-centered monoclinic lattice, the primitive cell has the shape of an oblique rhombic prism;See , row mC, column Primitive, where the cell parameters are given as a1 = a2, α = β it can be constructed because the two-dimensional centered rectangular base layer can also be described with primitive rhombic axes. Note that the length a of the primitive cell below equals \frac \sqrt of the conventional cell above. Crystal classes The table below org ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with a East Thrace, small portion on the Balkans, Balkan Peninsula in Southeast Europe. It shares borders with the Black Sea to the north; Georgia (country), Georgia to the northeast; Armenia, Azerbaijan, and Iran to the east; Iraq to the southeast; Syria and the Mediterranean Sea to the south; the Aegean Sea to the west; and Greece and Bulgaria to the northwest. Cyprus is located off the south coast. Turkish people, Turks form the vast majority of the nation's population and Kurds are the largest minority. Ankara is Turkey's capital, while Istanbul is its list of largest cities and towns in Turkey, largest city and financial centre. One of the world's earliest permanently Settler, settled regions, present-day Turkey was home to important Neol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large scale (300 kton/year, in 1989) for uses in pencils, lubricants, and electrodes. Under high pressures and temperatures it converts to diamond. It is a weak conductor of heat and electricity. Types and varieties Natural graphite The principal types of natural graphite, each occurring in different types of ore deposits, are * Crystalline small flakes of graphite (or flake graphite) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken. When broken the edges can be irregular or angular; * Amorphous graphite: very fine flake graphite is sometimes called amorphous; * Lump graphite (or vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paragonite
Paragonite is a mineral, related to muscovite. Its empirical formula is . A wide solvus separates muscovite from paragonite, such that there is little solid solution along the vector Na+ K+ and apparent micas of intermediate composition is most commonly a microscopic (or even sub-microscopic) intergrowth of two distinct micas, one rich in K, and the other in Na. Paragonite is a common mineral in rocks metamorphosed under blueschist facies conditions along with other sodic minerals such as albite, jadeite and glaucophane. During the transition from blueschist to greenschist facies, paragonite and glaucophane are transformed into chlorite and albite. Jadeite bearing pyroxene minerals have suggested Clinozoisite and paragonite are associated and derived from lawsonite releasing Quartz and water via the following reaction: 4CaAl2Si2O8(H2O)2 + NaAlSi2O6 2Ca2Al3Si3O12(OH) + NaAl3Si3O10(OH)2 + SiO2 + 6H2O It was first described in 1843 for an occurrence at Mt. Campione, Tessin, Switz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscovite
Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage yielding remarkably thin laminae (sheets) which are often highly elastic. Sheets of muscovite 5 meters × 3 meters (16.5 feet × 10 feet) have been found in Nellore, India. Muscovite has a Mohs hardness of 2–2.25 parallel to the 01face, 4 perpendicular to the 01and a specific gravity of 2.76–3. It can be colorless or tinted through grays, browns, greens, yellows, or (rarely) violet or red, and can be transparent or translucent. It is anisotropic and has high birefringence. Its crystal system is monoclinic. The green, chromium-rich variety is called fuchsite; mariposite is also a chromium-rich type of muscovite. Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudomorph
In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by another. The name literally means "false form". Terminology for pseudomorphs is "''replacer'' after ''original''", as in ''brookite'' after ''rutile''. Substitution pseudomorph An infiltration pseudomorph, or substitution pseudomorph is a pseudomorph in which one mineral or other material is replaced by another. The original shape of the mineral remains unchanged, but color, hardness, and other properties change to those of the replacing mineral. An example of this process is the replacement of wood by silica (quartz or opal) to form petrified wood in which the substitution may be so perfect as to retain the original cellular structure of the wood. An example of mineral-to-mineral substitution is replacement of aragonite twin crystal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andalusite
Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5. This mineral was called andalousite by Delamétehrie, who thought it came from Andalusia, Spain. It soon became clear that it was a locality error, and that the specimens studied were actually from El Cardoso de la Sierra, in the Spanish province of Guadalajara, not Andalusia. Andalusite is trimorphic with kyanite and sillimanite, being the lower pressure mid temperature polymorph. At higher temperatures and pressures, andalusite may convert to sillimanite. Thus, as with its other polymorphs, andalusite is an aluminosilicate index mineral, providing clues to depth and pressures involved in producing the host rock. Varieties The variety chiastolite commonly contains dark inclusions of carbon or clay which form a cruciform pattern when shown in cross-section. This stone was known at least from the sixteenth century, being taken to many European countries, as a souvenir, by pilgrims returning from Sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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