Mineral Tables - Minerals and Their Properties Mineral Hardness Cleavage Other properties Importance Composition Fracture Molybdenite 1 - 1.5 1 perfect Silvery gray to steel-bluish; Source of Mo (MoS2) cleavage high specific gravity (lubricant) (S.G.); black to greenish streak; greasy feel Graphite (C) 1 - 2 1 perfect Silvery - gray to dull black; Pencils, cleavage low S.G.; black streak, lubricants greasy feel Galena (PbS) 2.5 3 perfect at 90 Bright silvery to dull gray; Source of lead o streak; very high S.G. Native Gold (Au) 2.5 - 3 uneven Yellow metallic; very Gold metal fracture malleable Native Copper 2.5 - 3 uneven Copper-red metallic; Copper metal (Cu) fracture tarnishes dull; very malleable Native Silver (Ag) 2.5 - 3 uneven Silvery white to creamy Silver metal fracture metallic; tarnishes darker; very malleable Bornite (Cu5FeS4) 3 uneven to Bronzy metallic when Source of fresh; tarnishes iridescent Copper purple Chalcopyrite 3.5 - 4 uneven Brassy-yellow, tarnishes Source of (CuFeS2) iridescent; greenish black Copper streak Pyrrhotite (FeS) 3.5 - 4.5 uneven Bronzy metallic to dull Occurs with ores gray-brown; usually magnetic; gray-black streak Sphalerite (ZnS) 3.5 - 4 6 good Black to brownish Source of Zinc cleavages submetallic; brown to yellow-brown streak Limonite (Fe, O, 1 - 5 none Yellow to dark brown; Source of Iron H) yellow-brown streak; usually fine-grained and massive Hematite 5 - 6 uneven Bright silvery to Source of Iron metallic; reddish streak; generally massive to micaceous to colliform Magnetite (Fe3O4) 5.5 - 6.5 uneven Bright to dull metallic; Source of Iron black streak and colour; strongly magnetic
Mineral Tables - Minerals and Their Properties Mineral Composition Hardness Cleavage Fracture Other properties Importance Molybdenite (MoS2) 1 - 1.5 1 perfect cleavage Silvery gray to steel-bluish; high specific gravity (S.G.); black to greenish streak; greasy feel Source of Mo (lubricant) Graphite (C) 1 - 2 1 perfect cleavage Silvery - gray to dull black; low S.G.; black streak, greasy feel Pencils, lubricants Galena (PbS) 2.5 3 perfect at 90 o Bright silvery to dull gray; streak; very high S.G. Source of lead Native Gold (Au) 2.5 - 3 uneven fracture Yellow metallic; very malleable Gold metal Native Copper (Cu) 2.5 - 3 uneven fracture Copper-red metallic; tarnishes dull; very malleable Copper metal Native Silver (Ag) 2.5 - 3 uneven fracture Silvery white to creamy metallic; tarnishes darker; very malleable Silver metal Bornite (Cu5FeS4) 3 uneven to Bronzy metallic when fresh; tarnishes iridescent purple Source of Copper Chalcopyrite (CuFeS2) 3.5 - 4 uneven Brassy-yellow, tarnishes iridescent; greenish black streak Source of Copper Pyrrhotite (FeS) 3.5 - 4.5 uneven Bronzy metallic to dull gray-brown; usually magnetic; gray-black streak Occurs with ores Sphalerite (ZnS) 3.5 - 4 6 good cleavages Black to brownish submetallic; brown to yellow-brown streak Source of Zinc Limonite (Fe, O, H) 1 - 5 none Yellow to dark brown; yellow-brown streak; usually fine-grained and massive Source of Iron Hematite 5 - 6 uneven Bright silvery to metallic; reddish streak; generally massive to micaceous to colliform Source of Iron Magnetite (Fe3O4) 5.5 - 6.5 uneven Bright to dull metallic; black streak and colour; strongly magnetic Source of Iron