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Mineral Identification Data Sheet Mineral Group: Sulfides 19 Name & Formula Sphalerite ZnS (Zn,Fe)S Colour Lustre Streak Hardness Cleavage or Fracture brown, yellow, black (if Fe substitutes for Zn) Non-metallic (unlike most sulfides) – to submetallic brown to black (dependant on Fe composition) 3.5 – 4 soft perfect – 6 directions Metallic lustrous black with a slight green tinge 6 - 6.5 very hard (rare for a sulfide) none light or dark lead gray metallic lustrous black 2.5 soft perfect – cubic – 3 directions at 90° brass yellowish (sometimes with an iridescent tarnish) - The colour is distinctly more yellowish than Pyrite metallic lustrous black 3.5 - 4 poor, conchoidal fracture bronzy yellow metallic lustrous black 3.5 - 4 good basal cleavage is rarely seen due to massive habit brown to black with an iridescent tarnish metallic lustrous black 3 poor massive pieces often show many cleavage faces leading to a sparkling effect Resinous Sparkly 20 Pyrite yellow-to yellowish gray FeS2 “Fool’s Gold” 21 Galena duller colour than gold PbS 22 Chalcopyrite CuFeS2 23 Pyrrhotite Fe1-xS 24 Bornite Cu5FeS4 “Peacock Ore” Mineral Group: Sulfides Crystal Habit (draw picture) crystals common – tetrahedral; massive; colloform. Crystal Drawing Density 3.9 – 4.2 average Pyrite often forms good crystals, cubes, pyritohedrons, Crystals are usually striated. 5.0 average for a metallic Galena forms cubes, octahedra and cubeoctahedrons. 7.2 very heavy rare – almost always massive 4.2 – average for metallics Special Properties often found with Galena in carbonate rocks most common metallic mineral Uses Geological Environment major ore of Zinc (used to galvanize steel – a rustproofing process), Cu + Zn = brass hydrothermal sulfide ore veins in igneous rocks; sedimentary deposits – limestone, dolomite, marble with Pb; or in veins with Cu + Pb + Ag very little often associated with gold in quartz ore veins common in sulfide ores. major ore of Pb radiation shielding once found in gasoline (tetraethyl lead – anti-knock compound) – cause pollution found in sulfide ore veins with Cu and Zn in igneous and sedimentary deposits major ore of Cu found in sulfide ore veins with pyrite and other sulfide minerals crystals are uncommon (hexagonal books) usually massive massive, rare tetrahedral crystals 4.6 – 4.7– average for metallics It is magnetic (weaker than magnetite) this distinguishes it from similar looking Pyrite and Chalcopyrite 4.9 – 5.3– average for metallics iridescent tarnish is the key distinguishing property Pyrrhotite is mined primarily because it is associated with pentlandite, a sulfide mineral that can contain significant amounts of nickel and cobalt. Pyrrhotite is an iron sulfide mineral found in basic igneous rocks Bornite is a copper sulfide always found in association with other copper minerals – especially Chalcopyrite.