Geology Minerals

Hornblende Black to green, 2-D not at right angles (do not confuse with augite) Kaolinite looks like chalk, no HCI reaction Biotite Black, elastic, 1-D, perfect cleavage Chlorite greenish, flexible, 1-D (look for small flakes) Halite transparent, soft, 3-D perfect (cubic) Flourite soft, 4-D Galena Metallic, hi s.g., 3-D perfect (cubic) Muscovite colorless, silvery, elastic, 1-D perfect cleavage Chalcopyrite metallic, yellowish, soft, no cubes Sphalerite 6-D, yellowish where damaged, resinous Quartz transparent, translucent, hard, no cleavage Augite green to black, 2-D at right angles Olivine green and glassy aggregates, no cleavage Pyrite metallic, yellowish, hard Limonite earthy, yellowish-brown to orange streak is diagnostic Hematite red-brown streak, variety of habitats and hardness Plagioclase striations, 2-D at right angles Orthoclase no striations, 2-D at right angles Talc feels greasy, soapy, very soft 1-D Calcite 3-D rhombohedral, HCI reaction Gypsum Very soft, 3-D cleagave Garnet spherical faceted crystals, no cleavage, variety of colors Magnetite metallic, magnetic Corundum barrel-shaped hexagonal habit, h=9 Dolomite 3-D rhombohedral, power reacts with HCI Serpentine green, waxy some samples fibrous Copper soft and malleable, reddish streak/color, hi s.g. Tourmaline Elongate trigonal crystals (cross section), hard, no cleavage