Sewardite
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Sewardite
Sewardite is a rare arsenate mineral with formula of CaFe2+3(AsO4)2(OH)2. Sewardite was discovered in 1982 and named for the mineralogist, Terry M. Seward (born 1940), a professor of geochemistry in Zürich, Switzerland. Properties Sewardite is orthorhombic, which means in crystallographic terms, it contains 3 axes of unequal length, one "c" axis, and 1 "a" axis, and 1 "b" axis. The "c" axis runs vertically, and the "b" axis forms a 90 degree angle with the "c" axis; the "a" axis forms an angle that is less than 90 degrees. Its class structure in the crystal system, orthorhombic, is mmm (2/m 2/m 2/m) - dipyramidal. Sewardite can form platy to compact anhedral to subhedral masses up to 0.3 mm in size in a single specimen. In terms of its optical properties, sewardite is weakly anisotropic, which means the velocity of light varies depending on the direction through the mineral. Its color in plane-polarized light is dark red, and it does not exhibit pleochroism, which means ...
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Arsenate Minerals
Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the (AsO4)3− anion group and, more rarely, other arsenates with anions like AsO3(OH)2− (also written HAsO42−) (example: pharmacolite Ca(AsO3OH).2H2O) or (very rarely) sO2(OH)2sup>− (example: andyrobertsite). Arsenite minerals are much less common. Both the Dana and the Strunz mineral classifications place the arsenates in with the phosphate minerals. Example arsenate minerals include: * Annabergite Ni3(AsO4)2·8H2O *Austinite CaZn(AsO4)(OH) *Clinoclase Cu3(AsO4)(OH)3 *Conichalcite CaCu(AsO4)(OH) * Cornubite Cu5(AsO4)2(OH)4 *Cornwallite Cu2+5(AsO4)2(OH)2 *Erythrite Co3(AsO4)2·8H2O *Mimetite Pb5(AsO4)3Cl * Olivenite Cu2(AsO4)OH Nickel–Strunz Classification -08- Phosphates IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). This list uses it to modify the Classification of Nickel–Strunz ( mindat.org, 10 ed, pending publication). *Abbreviations: **"*" - discredi ...
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Arsenate Mineral
Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the (AsO4)3− anion group and, more rarely, other arsenates with anions like AsO3(OH)2− (also written HAsO42−) (example: pharmacolite Ca(AsO3OH).2H2O) or (very rarely) sO2(OH)2sup>− (example: andyrobertsite). Arsenite minerals are much less common. Both the Dana and the Strunz mineral classifications place the arsenates in with the phosphate minerals. Example arsenate minerals include: * Annabergite Ni3(AsO4)2·8H2O *Austinite CaZn(AsO4)(OH) *Clinoclase Cu3(AsO4)(OH)3 *Conichalcite CaCu(AsO4)(OH) * Cornubite Cu5(AsO4)2(OH)4 *Cornwallite Cu2+5(AsO4)2(OH)2 *Erythrite Co3(AsO4)2·8H2O *Mimetite Pb5(AsO4)3Cl *Olivenite Cu2(AsO4)OH Nickel–Strunz Classification -08- Phosphates IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). This list uses it to modify the Classification of Nickel–Strunz ( mindat.org, 10 ed, pending publication). *Abbreviations: **"*" - discredite ...
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Tsumeb Mine
, nickname = , settlement_type = City , motto = ''Glück Auf'' (German for ''Good luck'') , image_skyline = Welcome to tsumeb.jpg , imagesize = , image_caption = , image_flag = , flag_size = , image_seal = , seal_size = , image_shield = Tsumeb COA.svg , shield_size = , image_blank_emblem = , blank_emblem_type = , blank_emblem_size = , image_map = , mapsize = , map_caption = , pushpin_map = Namibia , pushpin_label_position = bottom , pushpin_mapsize = 240 , pushpin_map_caption = Location in Namibia , subdivision_type = Country , subdivision_name = , subdivision_type1 = Region , subdivision_name1 = Oshikoto Region , subdivision_type2 = Constituency , subdivision_name2 = Tsumeb , subdivision_type3 = , subdivision_name3 = ...
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Iron(III) Minerals
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron Age. In ...
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Calcium Minerals
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin ''calx'' " lime", which was obtained from heating limestone. Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharmaceu ...
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Sonora
Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. The state is divided into 72 municipalities; the capital (and largest) city of which being Hermosillo, located in the center of the state. Other large cities include Ciudad Obregón, Nogales (on the Mexico-United States border), San Luis Río Colorado, and Navojoa. Sonora is bordered by the states of Chihuahua to the east, Baja California to the northwest and Sinaloa to the south. To the north, it shares the U.S.–Mexico border primarily with the state of Arizona with a small length with New Mexico, and on the west has a significant share of the coastline of the Gulf of California. Sonora's natural geography is divided into three parts: the Sierra Madre Occidental in the east of the state; plains and rolling hills in the center; and the coast on the Gulf of California. It is pri ...
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Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Mexico covers ,Mexico
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making it the world's 13th-largest country by are ...
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Durango
Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated in the northwest of the country. With a population of 1,832,650, the 8th lowest of Mexico's states, Durango has Mexico's second-lowest population density, after Baja California Sur. The capital city, Victoria de Durango, is named after the first President of Mexico, Guadalupe Victoria. Geography General information With , Durango accounts for about 6.3% of the entire territory of Mexico. It is the fourth largest state lying at the extreme northwest of the Central Mexican Plateau, where it meets the Sierra Madre Occidental—the highest peaks in the state. The state has an average elevation of 1,775 meters above sea level, with a mean elevation of 1,750 m in the Valleys region and 2,450 m in the Sierra region. The city of Durango is on t ...
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Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and east. Although it does not border Zimbabwe, less than 200 metres (660 feet) of the Botswanan right bank of the Zambezi River separates the two countries. Namibia gained independence from South Africa on 21 March 1990, following the Namibian War of Independence. Its capital and largest city is Windhoek. Namibia is a member state of the United Nations (UN), the Southern African Development Community (SADC), the African Union (AU) and the Commonwealth of Nations. The driest country in sub-Saharan Africa, Namibia has been inhabited since pre-historic times by the San, Damara and Nama people. Around the 14th century, immigrating Bantu peoples arrived as part of the Bantu expansion. Since then, the Bantu groups, the largest being the Ovambo, h ...
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Tsumeb
, nickname = , settlement_type = City , motto = ''Glück Auf'' (German for ''Good luck'') , image_skyline = Welcome to tsumeb.jpg , imagesize = , image_caption = , image_flag = , flag_size = , image_seal = , seal_size = , image_shield = Tsumeb COA.svg , shield_size = , image_blank_emblem = , blank_emblem_type = , blank_emblem_size = , image_map = , mapsize = , map_caption = , pushpin_map = Namibia , pushpin_label_position = bottom , pushpin_mapsize = 240 , pushpin_map_caption = Location in Namibia , subdivision_type = Country , subdivision_name = , subdivision_type1 = Region , subdivision_name1 = Oshikoto Region , subdivision_type2 = Constituency , subdivision_name2 = Tsumeb , subdivision_type3 = , subdivision_name3 = ...
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Petrographic Microscope
A petrographic microscope is a type of optical microscope used in petrology and optical mineralogy to identify rocks and minerals in thin sections. The microscope is used in optical mineralogy and petrography, a branch of petrology which focuses on detailed descriptions of rocks. The method is called "polarized light microscopy" (PLM). __TOC__ Description Depending on the grade of observation required, petrological microscopes are derived from conventional brightfield microscopes of similar basic capabilities by: * Adding a Nicol prism polarizer filter to the light path beneath the sample slide * Replacing the normal stage with a circular rotating stage (typically graduated with vernier scales for reading orientations to better than 1 degree of arc) * Adding a second rotatable and removable Nicol prism filter, called the analyzer, to the light path between objective and eyepiece * Adding a phase telescope, also known as a Bertrand lens, which allows the viewer to s ...
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Orthorhombic
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (''a'' by ''b'') and height (''c''), such that ''a'', ''b'', and ''c'' are distinct. All three bases intersect at 90° angles, so the three lattice vectors remain mutually orthogonal. Bravais lattices There are four orthorhombic Bravais lattices: primitive orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic. For the base-centered orthorhombic lattice, the primitive cell has the shape of a right rhombic prism;See , row oC, column Primitive, where the cell parameters are given as a1 = a2, α = β = 90° 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 prim ...
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