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Puy De Pariou
The Puy de Pariou, also known as Puy Pariou or Le Pariou, is a volcano located in the Chaîne des Puys, in the Massif Central region. It is formed by the overlay of two strombolian cones and a tuff ring; it produced three lava flows during its eruptive history. Geography The Puy de Pariou is located about 10 km at the west of Clermont-Ferrand and a little more than 2 km from Orcines, at the south of the road that crosses the Col des Goules. The Puy des Goules is less than 400 meters north; the Cliersou, the Grand Suchet and the Petit Suchet are situated a few hundred meters west and south-west, and the Puy de Dôme lies about 1.5 km south. Topography Its highest point reaches 1,209 meters, 250 meters above the crystalline basement that forms the surrounding plain. It has a typical volcano shape of strombolian type, and its crater is formed by two craters, one nested in the other. The central crater, which is the highest and most recent, has an almost pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puy De Pariou 2001-07-30
Puy () is a geology, geological term used locally in the Auvergne (région), Auvergne, France for a volcano, volcanic hill. The word derives from the Franco-Provençal language, Provençal ''puech'', meaning an isolated hill, coming from Latin ''podium'', which has given also ''puig'' in Catalan, ''poggio'' in Italian, ''poio'' in Galician and Portuguese. Most of the puys of central France are small cinder cones, with or without associated lava, whilst others are domes of trachyte, trachytic rock, like the of the Puy-de-Dôme (mountain), Puy-de-Dôme. The puys may be scattered as isolated hills, or, as is more usual, clustered together, sometimes in lines. The chain of puys in central France probably became extinct in late prehistoric time. Other volcanic hills more or less like those of Auvergne are also known to geologists as puys; examples may be found in the Eifel and in the small cones on the Bay of Naples, whilst the relics of puys denuded by erosion are numerous in the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somma
A somma volcano (also known as a sommian) is a volcanic caldera that has been partially filled by a new central cone. The name comes from Mount Somma, a stratovolcano in southern Italy with a summit caldera in which the upper cone of Mount Vesuvius has grown. A number of Earth's best examples of somma volcanoes are found on Russia's Kamchatka Peninsula and the Kuril Islands that stretch south from Kamchatka to Hokkaidō (Japan). Some examples of somma volcanoes are the following: * Africa ** Pico do Fogo ( Fogo Island, Cape Verde) ** Teide (Tenerife, Canary Islands, Spain) * Americas ** Cosigüina (Chinandega, Nicaragua) ** Wizard Island (Oregon, United States) ** Lava domes (Mount St. Helens, Washington, United States) * Asia ** Ebeko (Paramushir Island, Kuril Islands, Russia) ** Gunung Baru Jari (Segara Anak caldera, Lombok, Indonesia) ** Kolokol Group: Kolokol, Berg, Borzov, Trezubetz (Urup Island, Kuril Islands, Russia) ** Anak Krakatoa (Krakatoa archipelago, Sunda Strait, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyroxene
The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) or magnesium (Mg) and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium (Cr), aluminium (Al), magnesium (Mg), cobalt (Co), manganese (Mn), scandium (Sc), titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ... (Ti), vanadium (V) or even iron (Fe II) or (Fe III). Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a common structure consisting of single chains of si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feldspar
Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspars and the ''alkali'' (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust, and 41% of the Earth's continental crust by weight. Feldspars crystalize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of sedimentary rocks. Compositions The feldspar group of minerals consists of tectosilicates, silicate minerals in which silicon ions are linked by shared oxygen ions to form a three-dimensional network. Compositions of major elements in common feldspars can be expressed in terms of three endmembers: * potassium feldspar (K-spar) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Glass
Volcanic glass is the amorphous (uncrystallized) product of rapidly cooling magma. Like all types of glass, it is a state of matter intermediate between the closely packed, highly ordered array of a crystal and the highly disordered array of liquid. Volcanic glass may refer to the interstitial material, or matrix, in an aphanitic (fine-grained) volcanic rock, or to any of several types of vitreous igneous rocks. Origin Volcanic glass is formed when magma is rapidly cooled. Magma rapidly cooled to below its normal crystallization temperature becomes a supercooled liquid, and, with further rapid cooling, this becomes an amorphous solid. The change from supercooled liquid to glass occurs at a temperature called the glass transition temperature, which depends on both cooling rate and the amount of water dissolved in the magma. Magma rich in silica and poor in dissolved water is most easily cooled rapidly enough to form volcanic glass. As a result, rhyolite magmas, which are high in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hornblende
Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks. The general formula is . Physical properties Hornblende has a hardness of 5–6, a specific gravity of 3.0 to 3.6, and is typically an opaque green, dark green, brown, or black color. It tends to form slender prismatic to bladed crystals, diamond-shaped in cross-section, or is present as irregular grains or fibrous masses. Its planes of cleavage intersect at 56° and 124° angles. Hornblende is most often confused with the pyroxene series and biotite mica, which are also dark minerals found in granite and charnockite. Pyroxenes differ in their cleavage planes, which intersect at 87° and 93°. Hornblende is an inosilicate (chain silicate) mineral, built around double chains of silica tetrahedra. These chains extend the length of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andesine
Andesine is a silicate mineral, a member of the plagioclase feldspar solid solution series. Its chemical formula is ( Ca, Na)( Al, Si)4 O8, where Ca/(Ca + Na) (% anorthite) is between 30–50%. The formula may be written as Na0.7-0.5Ca0.3-0.5Al1.3-1.5Si2.7-2.5O8. The plagioclase feldspars are a continuous solid solution series and as such the accurate identification of individual members requires detailed optical study, chemical analysis or density measurements. Refractive indices and specific gravity increase directly with calcium content.Klein, Cornelis, and Cornelius S. Hurlbut, Jr., ''Manual of Mineralogy,'' Wiley, 20th ed. 1985, p. 455 It is sometimes used as a gemstone. Name and discovery Andesine was first described in 1841 for an occurrence in the Marmato mine, Marmato, Cauca, Chocó Department, Colombia. The name is for the Andes due to its abundance in the andesite lavas in those mountains. In the early 2000s, red and green gemstones began to be marketed under the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachyandesite
Trachyandesite is an extrusive igneous Rock (geology), rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by Sodium, sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alkali metals and with an intermediate content of silica. The term ''trachyandesite'' had begun to fall into disfavor by 1985 but was revived to describe extrusive igneous rocks falling into the S3 field of the TAS classification. These are divided into sodium-rich benmoreite and potassium-rich latite. Trachyandesitic magma can produce explosive Plinian eruptions, such as happened at Mount Tambora, Tambora in 1815. The 2010 eruptions of Eyjafjallajökull, Eyjafjallajökull 2010 eruption (VEI4), which disrupted European and transatlantic air travel from 14–18 October 2010, for some time was dominated by trachyandesite. Petrology Trachyandesite is characterized by a silica content near 58% and a total alkali oxide cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olivine Phenocryst
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. For this reason, olivine has been proposed as a good candidate for accelerated weathering to sequester carbon dioxide from the Earth's oceans and atmosphere, as part of climate change mitigation. Olivine also has many other historical uses, such as the gemstone peridot (or chrysolite), as well as industrial applications like metalworking processes. The ratio of magnesium to iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember: ) and fayalite (Fe-endmember: ). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and fayalite (Fa) (''e.g.'', Fo70Fa30). Forsterite's melting temperature is unusually high at atmospheric pressure, almost , while fay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labradorite
Labradorite (( Ca, Na)( Al, Si)4 O8) is a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect ( schiller). Labradorite is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573 and twinning is common. As with all plagioclase members, the crystal system is triclinic, and three directions of cleavage are present, two of which are nearly at right angles and are more obvious, being of good to perfect quality (while the third direction is poor). It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, as well as in anorthosites. Occurrence The geological type area for labradorite is Paul's Island near the town of Nain in Labrador, Canada. It has also been r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bytownite
Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It is usually defined as having between 70 and 90% An (formula: (Ca0.7-0.9,Na0.3-0.1) l(Al,Si)Si2O8. Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations. The specific gravity of bytownite varies between 2.74 and 2.75. The refractive indices ranges are nα=1.563 – 1.572, nβ=1.568 – 1.578, and nγ=1.573 – 1.583. Precise determination of these two properties with chemical, X-ray diffraction, or petrographic analysis are required for identification. Occurrence Bytownite is a rock forming mineral occurring in mafic igneous rocks such as gabbros and anorthosites. It also occurs as phenocrysts in mafic volcanic rocks. It is rare in metamorphic rocks. It is typically associated with pyroxenes and olivine. The mineral was first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anorthite
Anorthite is the calcium endmember of the plagioclase feldspar mineral series. The chemical formula of pure anorthite is Ca Al2 Si2O8. Anorthite is found in mafic igneous rocks. Anorthite is rare on the Earth but abundant on the Moon. Mineralogy Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite (NaAlSi3O8). Anorthite also refers to plagioclase compositions with more than 90 molecular percent of the anorthite endmember. At standard pressure, anorthite melts at .J.R. Goldsmith (1980): The melting and breakdown reactions of anorthite at high pressures and temperatures. Am. Mineralogist. 65, 272-284, http://www.minsocam.org/ammin/AM65/AM65_272.pdf Occurrence Anorthite is a rare compositional variety of plagioclase. It occurs in mafic igneous rock. It also occurs in metamorphic rocks of granulite facies, in metamorphosed carbonate rocks, and corundum deposits. Its type localities are Monte Somma and Valle di Fass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
