| 翻訳と辞書 |
Khatyrkite
Khatyrkite ( )〔(Khatyrkite Mineral Data )〕 is a rare mineral which is mostly composed of copper and aluminium, but might contain up to about 15% of zinc or iron;〔 its chemical structure is described by an approximate formula (Cu,Zn)Al2 or (Cu,Fe)Al2. It was discovered in 1985 in placers derived from serpentinite, in association with another rare mineral cupalite ((Cu,Zn,Fe)Al). Both minerals are thus far restricted to the area of Listvenitovyi Stream, in the Khatyrka ultramafic (silicon-poor) zone of the Koryak–Kamchatka fold area, Koryak Mountains, Beringovsky District, Chukotka Autonomous Okrug, Far Eastern Federal District, Russia. The mineral's name derives from the Khatyrka ((ロシア語:Хатырка)) zone where it was discovered.〔Razin, L.V., N.S. Rudashevskii, and L.N. Vyal'sov. (1985) New natural intermetallic compounds of aluminum, copper and zinc—khatyrkite CuAI2, cupalite CuAI and zinc aluminides—from hyperbasites of dunite-harzburgite formation. Zap. Vses. Mineral. Obshch., 114,90–100 (in Russian). c.f. (1986) Amer. Mineral., 71, 1278〕 Its type specimen (defining sample) is preserved in the Mining Museum in Saint Petersburg, and parts of it can be found in other museums, such as Museo di Storia Naturale di Firenze.〔〔〔
==Properties==
In the initial studies of khatyrkite, a negative correlation was observed between copper and zinc, i.e. the higher the copper the lower the zinc content and vice versa, which is why the formula was specified as (Cu,Zn)Al2. It was found later that iron can be substituted for zinc.〔 The mineral is opaque and has a steel-gray yellow tint in reflected light, similar to native platinum. Isotropic sections are light blue whereas anisotropic ones are blue to creamy pink. Strong optical anisotropy is observed when the crystals are viewed in polarized light. Khatyrkite forms dendritic, rounded or irregular grains, typically below 0.5 millimeter in size, which are intergrown with cupalite. They have a tetragonal symmetry with point group 4/m 2/m 2/m, space group I4/mcm and lattice constants ''a'' = 0.607(1) nm, ''c'' = 0.489(1) nm and four formula units per unit cell. The crystalline structure parameters are the same for khatyrkite and synthetic CuAl2 alloy. The density, as calculated from XRD the lattice parameters, is 4.42 g/cm3. The crystals are malleable, that is they deform rather than break apart upon a strike; they have the Mohs hardness is between 5 and 6 and Vickers hardness is in the range 511–568 kg/mm2 for a 20–50 gram load and 433–474 kg/mm2 for a 100 gram load.〔
Khatyrkite and cupalite are accompanied by spinel, corundum, stishovite, augite, forsteritic olivine, diopsidic clinopyroxene and several Al-Cu-Fe metal alloy minerals. The presence of unoxidized aluminium in khatyrkite and association with the stishovite—a form of quartz which exclusively forms at high pressures of several tens gigapascals—suggest that the mineral is formed either upon meteoritic impact or in the deep earth mantle.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Khatyrkite」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|