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Apr 03 2013

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Ore Minerals and Rocks

Different types of pyrites.

Different types of pyrites.

Arsenopyrite

311_rx_Arsenopyrite311_rx_Arsenopyrite_2311_rx_Arsenopyrite_3

Not and ore, but common sulphide associated with ores Usually granular masses of a silvery or whitish-grey. H (5.5-6), very heavy with good cleavage, metallic luster brighter than pyrite or pyrrhotite. Black streak that smells slightly of garlic.

Asbestos (serpentine)

311_rx_Asbestos_3311_rx_Asbestos311_rx_Asbestos_2

Industrial mineral (insulation) 

Azurite

311_rx_Azurite_Malachite311_rx_Azurite_Malachite_2311_rx_Azurite_Malachite_3

Copper indicator mineral (rarely ore). Hydrous copper carbonate, bright azure blue, heavy, semi-hard (3.5-4) with pale blue streak. Commonly occurs as a film or earthy granular or concretionary masses.

Bornite

311_rx_Bornite

Copper (Cu) ore. Brownish-purple compact granular masses (rarely cubic) which are usually tarnished to an irridescent purple and blue film (peacock ore). Soft (3), very heavy and fragile with good cleavage, metallic luster.

Chalcopyrite

311_rx_Chalcopyrite311_rx_Chalcopyrite_2311_rx_Chalcopyrite_3

Copper (Cu) ore. Dark or brassy-yellow often with an irridescent film (bright greens, reds, blues in contrast to the deep purple of bornite). Generally granular masses, H (3.5-4), heavy, no cleavage, conchoidal fracture with metallic to semi-metallic luster. Greenish-black streak.

Chromite

311_rx_Chromite

Chromium (Cr) ore. Black, granular masses with a vaguely glassy luster compared with magnetite and ilmenite. Heavy, hard (5.5), no cleavage, dark brown streak.

Galena

311_rx_Galena

Lead (Pb) ore. Hardness of 2 to 3 making it very soft. Cubic crystals with prefect or almost perfect cleavage. High density rock with a bright metallic luster and dark grey streak. Usually found as compact granular masses.

Goetite/ Limonite

311_rx_Goetite

Iron ore and iron indicator mineral 

Graphite

311_rx_Graphite
Industrial mineral (lubricant, thermal conductor)

Hematite

311_rx_Hematite311_rx_Hematite_2311_rx_Hematite_3

Iron ore. It is possible to find hematitle in silver colour in nature. The best method to identify them is to use the colour of the streak which is red.

Ilmenite

311_rx_Ilmenite311_rx_Ilmenite_2

Titanium ore. Locally very weakly magnetic, blackish granular masses with dull submetallic luster. Heavy, H (5-6), no cleavage, black to brownish-red streak.

Limonite

311_rx_Limonite

Magnetite

Iron (Fe) ore. Highly magnetic, iron-black, granular masses with dull submetallic luster and blueish irridescence. Very heavy, H (5.5-6), no cleavage, black streak.

Malachite

Copper indicator mineral (rarely ore). Emerald-green-pale green film or rarely acicular fibrous crystals. H (3.5-4), sometimes silky luster, light green streak.

Molybdenite

311_rx_Molybdenum311_rx_Molybdenum_2

Industrial mineral (lubricant) and molybdenum

Native Copper

311_rx_Copper

Copper (Cu) ore. Soft (2.5-3) copper-red, very heavy, ductile and malleable with a hackly fracture, metallic luster. Occurs in compact or dendritic masses. Often has a greenish film of malachite.

Pyyrhotite

311_rx_Pyyrhotite_2311_rx_Pyyrhotite

Not and ore, but common sulphide associated with ores. Usually magnetic, not as strong as magnetite. Bronze-silvery and duller than pyrite, massive, granular aggregates, sometimes irridescent. Very heavy, H (3.5-4.5), fragile with parting, bright metallic luster.

Pyrite

311_rx_Pyrite311_rx_Pyrite_2311_rx_Pyrite_3

Not and ore, but common sulphide associated with ores. striated cubic or sometimes octahedarl crystals but more commonly granular aggregates with bright metallic luster and a fairly brassy-yellow, H (6-6.5), greenish-black streak.

Sphalerite

311_rx_Sphalerite

Zinc (Zn) ore. Hardness of about 3 – 4.5. Pale yellow-brown streak, very variable from yellow or reddish brown to blackish (with high iron) to colourless. Heavy, fragile with perfect cleavage parallel to crystal faces. Usually has a waxy to resinous luster and can be transparent.

References:
Geology 311 Lab Manual, University of Calgary

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