Ann: Extensive Sulphide Zone at Southern Anomaly, page-10

Chalcocite

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	Chalcocite
1	Chalcosite from Cornwall
2	General
3	Category	Sulfide minerals
4	Formula(repeating unit)	copper(I) sulfide: Cu2S
5	Strunz classification	2.BA.05a
6	Crystal system	Monoclinic
7	Crystal class	Prismatic (2/m) (same H-M symbol)
8	Space group	P21/c
9	Unit cell	a = 15.246(4) Å, b = 11.884(2) Å, c = 13.494(3) Å; β = 116.35(1)°; Z = 48
10	Identification
11	Color	Dark gray to black
12	Crystal habit	Tabular to prismatic crystals also massive to granular, (pseudo-orthorhombic)
13	Twinning	Common on {110} yielding pseudohexagonal stellate forms
14	Cleavage	Indistinct on {110}
15	Fracture	Conchoidal
16	Tenacity	Brittle to sectile
17	Mohs scalehardness	2.5 - 3
18	Luster	Metallic
19	Streak	Shiny black to lead gray
20	Diaphaneity	Opaque
21	Specific gravity	5.5 - 5.8
22	Fusibility	2-2.5
23	References	[1][2][3][4]

Chalcocite (UK: /ˈkælkəˌsaɪt/^[5]), 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 ¹⁄₂ - 3 on the Mohs scale. It is a sulfide with an orthorhombic crystal system.
The term chalcocite comes from the alteration of the obsolete name chalcosine, from the Greek khalkos, meaning copper. It is also known as redruthite, vitreous copper and copper-glance.^[6]
Occurrence[edit]

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 (66.6% atomic ratio and nearly 80% by weight) and the ease at which copper can be separated from sulfur.


Description[edit]

Occurrence[edit]



A sample of molybdenite mineral less pure than the single-crystal specimen above.
Molybdenite occurs in high temperature hydrothermal ore deposits. Its associated minerals include pyrite, chalcopyrite, quartz, anhydrite, fluorite, and scheelite. Important deposits include the disseminated porphyry molybdenum deposits at Questa, New Mexico and the Henderson and Climax mines in Colorado. Molybdenite also occurs in porphyry copper deposits of Arizona, Utah, and Mexico.


Chalcopyrite

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	Chalcopyrite
1
2	General
3	Category	Sulfide mineral
4	Formula(repeating unit)	CuFeS2
5	Strunz classification	2.CB.10a
6	Crystal system	Tetragonal
7	Crystal class	Scalenohedral (42m) H-M symbol: (4 2m)
8	Space group	I42d
9	Unit cell	a = 5.289 Å, c = 10.423 Å; Z = 4
10	Identification
11	Formula mass	183.54 g/mol
12	Color	Brass yellow, may have iridescent purplish tarnish.
13	Crystal habit	Predominantly the disphenoid and resembles a tetrahedron, commonly massive, and sometimes botryoidal.
14	Twinning	Penetration twins
15	Cleavage	Indistinct on {011}
16	Fracture	Irregular to uneven
17	Tenacity	Brittle
18	Mohs scalehardness	3.5
19	Luster	Metallic
20	Streak	Greenish black
21	Diaphaneity	Opaque
22	Specific gravity	4.1 – 4.3
23	Optical properties	Opaque
24	Solubility	Soluble in HNO3
25	Other characteristics	magnetic on heating
26	References	[1][2][3][4][5]

Chalcopyrite ( /ˌkælkəˈpaɪraɪt, -koʊ-/^[6][7] KAL-ko-PY-ryt) is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical formulaCuFeS₂. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.
On exposure to air, chalcopyrite oxidises to a variety of oxides, hydroxides and sulfates. Associated copper minerals include the sulfides bornite (Cu₅FeS₄), chalcocite (Cu₂S), covellite (CuS), digenite (Cu₉S₅); carbonates such as malachite and azurite, and rarely oxides such as cuprite (Cu₂O). Chalcopyrite is rarely found in association with native copper.