|
Millerite Structure
Millerite is a nickel sulfide mineral, Ni S. It is brassy in colour and has an acicular habit, often forming radiating masses and furry aggregates. It can be distinguished from pentlandite by crystal habit, its duller colour, and general lack of association with pyrite or pyrrhotite. Paragenesis Millerite is a common metamorphic mineral replacing pentlandite within serpentinite ultramafics. It is formed in this way by removal of sulfur from pentlandite or other nickeliferous sulfide minerals during metamorphism or metasomatism. Millerite is also formed from sulfur poor olivine cumulates by nucleation. Millerite is thought to form from sulfur and nickel which exist in pristine olivine in trace amounts, and which are driven out of the olivine during metamorphic processes. Magmatic olivine generally has up to ~4000 ppm Ni and up to 2500 ppm S within the crystal lattice, as contaminants and substituting for other transition metals with similar ionic radii (Fe2+ and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfide Mineral
The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulfarsenides and the sulfosalts.http://www.minerals.net/mineral/sort-met.hod/group/sulfgrp.htm Minerals.net Dana Classification, SulfidesKlein, Cornelis and Cornelius S. Hurlbut, Jr., 1986, ''Manual of Mineralogy'', Wiley, 20th ed., pp 269-293 Sulfide minerals are inorganic compounds. Minerals Common or important examples include: * Acanthite *Chalcocite *Bornite * Galena * Sphalerite *Chalcopyrite *Pyrrhotite *Millerite *Pentlandite *Covellite *Cinnabar *Realgar *Orpiment *Stibnite *Pyrite *Marcasite *Molybdenite Sulfarsenides: *Cobaltite *Arsenopyrite *Gersdorffite Sulfosalts: *Pyrargyrite *Proustite *Tetrahedrite *Tennantite *Enargite *Bournonite * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transvaal Province
The Province of the Transvaal ( af, Provinsie van Transvaal), commonly referred to as the Transvaal (; ), was a province of South Africa from 1910 until 1994, when a new constitution subdivided it following the end of apartheid. The name "Transvaal" refers to the province's geographical location to the north of the Vaal River. Its capital was Pretoria, which was also the country's executive capital. History In 1910, four British colonies united to form the Union of South Africa. The Transvaal Colony, which had been formed out of the bulk of the old South African Republic after the Second Boer War, became the Transvaal Province in the new union. Half a century later, in 1961, the union ceased to be part of the Commonwealth of Nations and became the Republic of South Africa. The PWV (Pretoria-Witwatersrand-Vereeniging) conurbation in the Transvaal, centred on Pretoria and Johannesburg, became South Africa's economic powerhouse, a position it still holds today as Gauteng Province ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Australia is Australia's largest state, with a total land area of . It is the second-largest country subdivision in the world, surpassed only by Russia's Sakha Republic. the state has 2.76 million inhabitants percent of the national total. The vast majority (92 percent) live in the south-west corner; 79 percent of the population lives in the Perth area, leaving the remainder of the state sparsely populated. The first Europeans to visit Western Australia belonged to the Dutch Dirk Hartog expedition, who visited the Western Australian coast in 1616. The first permanent European colony of Western Australia occurred following the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yilgarn Craton
The Yilgarn Craton is a large craton that constitutes the bulk of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Terrane have been dated at ~4.27 Ga, with one detrital zircon dated as old as 4.4 Ga. The Murchison Province of the craton contains the oldest dated meteorite impact crater, at 2229 ± 5 Ma. Geology The Yilgarn Craton appears to have been assembled between ~2.94 and 2.63 Ga by the accretion of a multitude of formerly present blocks or terranes of existing continental crust, most of which formed between 3.2 Ga and 2.8 Ga. This accretion event is recorded by widespread granite and granodiorite intrusions, which comprise over 70% of the Yilgarn craton; voluminous tholeiitic basalt and komatiite volcanism; regional metamorphism and deformation as well as the emplacement of the vast majority of the craton's endowment in gold mineralisation. These acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Caledonia
) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign state , subdivision_name = , established_title = Annexed by France , established_date = 24 September 1853 , established_title2 = Overseas territory , established_date2 = 1946 , established_title3 = Nouméa Accord , established_date3 = 5 May 1998 , official_languages = French , regional_languages = , capital = Nouméa , coordinates = , largest_city = capital , demonym = New Caledonian , government_type = Devolved parliamentary dependency , leader_title1 = President of France , leader_name1 = Emmanuel Macron , leader_title2 = President of the Government , leader_name2 = Louis Mapou , leader_title3 = President of the Congress , leader_name3 = Roch Wamytan , leader_title4 = High Commissioner , leader_name4 = Patrice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laterite
Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by intensive and prolonged weathering of the underlying parent rock, usually when there are conditions of high temperatures and heavy rainfall with alternate wet and dry periods. Tropical weathering (''laterization'') is a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils. The majority of the land area containing laterites is between the tropics of Cancer and Capricorn. Laterite has commonly been referred to as a soil type as well as being a rock type. This and further variation in the modes of conceptualizing about laterite (e.g. also as a complete weathering profile or theory about weathering) has led to calls for the term to be abandoned alto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heazlewoodite
Heazlewoodite, Ni3S2, is a rare sulfur-poor nickel sulfide mineral found in serpentinitized dunite. It occurs as disseminations and masses of opaque, metallic light bronze to brassy yellow grains which crystallize in the trigonal crystal system. It has a hardness of 4, a specific gravity of 5.82. Heazlewoodite was first described in 1896 from Heazlewood, Tasmania, Australia. Paragenesis Heazlewoodite is formed within terrestrial rocks by metamorphism of peridotite and dunite via a process of nucleation. Heazlewoodite is the least sulfur saturated of nickel sulfide minerals and is only formed via metamorphic exsolution of sulfur from the lattice of metamorphic olivine. Heazlewoodite is thought to form from sulfur and nickel which exist in pristine olivine in trace amounts, and which are driven out of the olivine during metamorphic processes. Magmatic olivine generally has up to ~4000 ppm Ni and up to 2500 ppm S within the crystal lattice, as contaminants and substituti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fugacity
In chemical thermodynamics, the fugacity of a real gas is an effective partial pressure which replaces the mechanical partial pressure in an accurate computation of the chemical equilibrium constant. It is equal to the pressure of an ideal gas which has the same temperature and molar Gibbs free energy as the real gas. Fugacities are determined experimentally or estimated from various models such as a Van der Waals gas that are closer to reality than an ideal gas. The real gas pressure and fugacity are related through the dimensionless fugacity coefficient . \varphi = \frac For an ideal gas, fugacity and pressure are equal and so . Taken at the same temperature and pressure, the difference between the molar Gibbs free energies of a real gas and the corresponding ideal gas is equal to . The fugacity is closely related to the thermodynamic activity. For a gas, the activity is simply the fugacity divided by a reference pressure to give a dimensionless quantity. This reference press ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Talc Carbonate
Talc carbonates are a suite of rock and mineral compositions found in metamorphosed ultramafic rocks. The term refers to the two most common end-member minerals found within ultramafic rocks which have undergone talc-carbonation or carbonation reactions: talc and the carbonate mineral magnesite. Talc carbonate mineral assemblages are controlled by temperature and pressure of metamorphism and the partial pressure of carbon dioxide within metamorphic fluids, as well as by the composition of the host rock. Compositional controls In a general sense, talc carbonate metamorphic assemblages are diagnostic of the magnesium content of the ultramafic protolith. * Lower-magnesian ultramafic rocks (12-18% MgO as a rule of thumb) tend to favor talc-chlorite assemblages * Medium-MgO rocks (15-25% MgO) tend to produce talc-amphibole assemblages. * High-MgO rocks with in excess of 25% MgO tend to form true talc-magnesite metamorphic assemblages. Thus, the MgO content of a metamorphosed ultram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
