07-12-2012, 03:02 PM
GEOLOGY ASSIGNMENT
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COPPER
Copper can be found as either native
copper or as part of minerals.
Most common minerals of copper are following.
Chalcopyrite(CuFeS2) and chalcocite(Cu2S) are copper sulfides minerals.
Azurite(2CuCO3·Cu(OH)2) and Malachite(CuCO3.Cu (OH)2) are copper carbonates.
Cuprite(Cu2O) is a copper oxide.
Top Copper producer countries are- Chile, US, Peru and Indonesia etc.
Copper is either formed within sedimentary rocks, or associated with igneous rocks.
Native copper
Characteristics
Colour-Pale rose on fresh surface, copper-red in reflected light.
Chemical Formula- Cu
Crystal System- Cubic Hexaoctahedral
Cleavage- None
Fracture- Hackely
Hardness- 2.5 to 3
Luster- Metallic
Special Gravity- 8.95
Chalcopyrite(CuFeS2)
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system.
Chalcopyrite is present in volcanogenic massive sulfide ore deposits and sedimentary exhalative deposits.
Physical Properties-
Colour- Brass yellow
Crystal System- Tetragonal
Cleavage- Indistinct
Fracture- Irregular to uneven
Mohr’s Scale- 3.5
Luster- Metallic
Streak- Greenish Black
Special Gravity- 4.1 to 4.3
Occurrence in India- Khetri(Rajasthan), Malanjkhand(M.P.), Jharkhand etc.
% Copper when pure- 34.5%
Chlorargyrite(AgCl)
Chlorargyrite is the mineral form of Silver Chloride(AgCl).
Chlorargyrite occurs as a secondary mineral phase in the oxidation of silver mineral.
Characteristics
Colour- Brown or Purple
Crystal System- Isometric-Hexaoctahedral
Hardness- 1 to 2
Special Gravity- 5.55
It is also known as cerargyrite and, when weathered by desert air.