….

Minerals

Silicates….

quartz (crystal form, concoidal fracture, harder than glass, various colors)

plagioclase feldspar (2 planes of cleavage, striations, elongate, transluscence, pleochroism)

potassium feldspar (2 planes cleavage, opaque, blocky, pink?)

muscovite (colorless – silver mica, 1 plane of cleavage, scratch with fingernail)

biotite (black mica, 1 plane of cleavage, scratch with fingernail)

augite (pyroxene, 2 planes of cleavage at right angles, black­dark green, blocky) hornblende (amphibole, 2 planes of cleavage ~60° & ~120°, black, elongate) garnet (crystal form, various colors, harder than glass, no cleavage)

olivine (color, no cleavage, glassy)

kaolinite (scratch with fingernail, white to gray, massive, "clay" feel)

Oxides

magnetite (magnetic, black­gray streak, color, iron oxide)

hematite (red­brown streak, hardness, metallic and non­metallic luster, various forms, iron oxide) limonite (color, hardness, streak, iron oxide)

corundum (hardness of 9, barrel shape crystal form, parting planes not considered as cleavage)

Carbonates

calcite (calcium carbonate: CaCO3, 2 planes of cleavage, effervescence, softer than glass) dolomite (calcium, magnesium carbonate: CaMg(CO3)2, similar to calcite, with less, effervescence)


Other

fluorite (4 planes of cleavage, various colors)

halite (3 planes of cleavage, taste, pink to white or clear, salt)

graphite (hardness of 1, streak on paper)

pyrite (gold color, "fools gold", no cleavage, cubic crystal form, iron sulfide)

galena (very heavy, 3 planes of cleavage at right angles often "stairstepped", lead sulfide)

gypsum /selenite (scratch with fingernail, pink to white color to clear, 1 good and 2 poor planes of cleavage)

Mineral Quiz

At the beginning of the next lab, we will have a mineral identification quiz. For the quiz, you will be given 10 to 12 mineral specimens to identify out of the two dozen or so you will examine today. You will be asked to give the mineral name and answer one question concerning the sample. You can bring ONE 8.5 x 11 sheet of paper with any information on the front and back (no sharing with your neighbor). The specimens for the quiz may be different from the ones you will see during the lab, so you will want to identify the individual minerals by distinguishing characteristics.