كالكوسيت Chalcocite

Chalcocite
Chalcocite from Cornwall
العامة
التصنيف	معدن كبريتيدي
الصيغة (repeating unit)	copper(I) sulfide: Cu2S
تصنيف سترونز	2.BA.05a
النظام البلوري	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/c
Unit cell	a = 15.246(4) Å, b = 11.884(2) Å, c = 13.494(3) Å; β = 116.35(1)°; Z = 48
التعرف
Color	Dark gray to black
Crystal habit	Tabular to prismatic crystals also massive to granular, (pseudo-orthorhombic)
Twinning	Common on {110} yielding pseudohexagonal stellate forms
Cleavage	Indistinct on {110}
Fracture	Conchoidal
Tenacity	Brittle to sectile
Mohs scale hardness	2+1⁄2–3
Luster	Metallic
Streak	Shiny black to lead gray
Diaphaneity	Opaque
الجاذبية النوعية	5.5–5.8
قابلية الانصهار	2–2.5
References

Chalcocite ( /ˈkælkəˌsaɪt/), copper(I) sulfide (Cu₂S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system.

The term chalcocite from the Greek khalkos, meaning "copper". It is also known as redruthite, vitreous copper, or copper-glance.

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 أصل الاسم والتاريخ

The mineral received its current name chalcocite in 1832 from François Sulpice Beudant , who derived the name from the Greek word χαλκός chalkos for copper.

The mineral had been known since at least the 16th century . There is evidence that Lazarus Ercker used the mining term "Kupffer glaß ertz" (i.e. copper glass ore or copper glass for short ) in his 1580 work Description of the Most Excellent Mineral Ores and Mining Types. Abraham Gottlob Werner's work, which was published by Christian August Siegfried Hoffmann in 1789 under the title Mineral System of Inspector Werner with his permission, also contains the term copper glass , divided into dense and foliated copper glass. In Johann Friedrich Ludwig Hausmann's work Handbook of Mineralogie (1st edition published in 1813) the mineral is then found under the name copper luster (see also luster ).

 البنية البلورية

البنية البلورية لكالكوسيت عميق.

Chalcocite, more precisely deep chalcocite (also deep copper luster ) crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 15.25 Å ; b = 11.88 Å; c = 13.49 Å and β = 116.3° as well as 48 formula units per unit cell.

At a temperature above 103 °C, low-chalcocite changes into the hexagonal modification and is accordingly referred to as high-chalcocite or high-copper galena . The space group of high-chalcocite is space group P 6 3 / mmc (space group no. 194) and the lattice parameters are a = 3.95 Å and c = 6.75 Å with 2 formula units per unit cell.

 التواجد

Chalcocite is sometimes found as a primary vein mineral in hydrothermal veins. However, most chalcocite occurs in the supergene enriched environment below the oxidation zone of copper deposits as a result of the leaching of copper from the oxidized minerals. It is also often found in sedimentary rocks.

It has been mined for centuries and is one of the most profitable copper ores. The reasons for this is its high copper content (66.7% atomic ratio and nearly 80% by weight) and the ease at which copper can be separated from sulfur.

Chalcocite crystals from the Mammoth Mine, Mount Isa – Cloncurry area, Queensland, Australia (size: 3.0 x 2.9 x 2.4 cm)

Since chalcocite is a secondary mineral that forms from the alteration of other minerals, it has been known to form pseudomorphs of many different minerals. A pseudomorph is a mineral that has replaced another mineral atom by atom, but it leaves the original mineral's crystal shape intact. Chalcocite has been known to form pseudomorphs of the minerals bornite, covellite, chalcopyrite, pyrite, enargite, millerite, galena and sphalerite.

 الاستخدام

Chalcocite was an important raw material for the extraction of copper until the most productive mining areas in England and the USA were exhausted . Today, chalcocite, along with other copper sulphides such as bornite and covellite, still plays a major role as an ore mineral in layered deposits such as those around Lubin in Lower Silesia, Poland.

 انظر أيضاً

• Copper(I) sulfide
• Copper monosulfide

 المراجع

• Dana's Manual of Mineralogy ISBN 0-471-03288-3
• Mineral Galleries