Mineral Identification

Identify what mineral is being described in each question below Identify what mineral is being described in each question below. Explain how you knew (For example, which property or properties did you look at).

Uses and other properties A student finds a black mineral that breaks into sheets easily and is relatively soft. Low hardness cleavage Mineral Colour(s) Streak Hardness Breakage pattern Uses and other properties calcite colourless, white, pale blue colourless, white 3 cleavage in three directions fizzes when HCI is added used in cements and other building materials feldspar colourless, white to grey, green colourless 6 two cleavage planes, meeting at ~90° angle used in the manufacture of ceramics quartz various colours none 7 conchoidal fracture used as gemstones and in glass manufacture, electronic equipment, radios, computers, and watches graphite black to grey 1-1.5 basal cleavage (scales) used as pencil lead, lubricants for locks, rods to control some small nuclear reactions, and battery poles galena grey grey to black 2.5 perfect cubic cleavage source of leads used in pipes, shields for X-rays hematite black, reddish brown reddish brown 5.5-6.5 irregular fracture source of iron converted to “pig” iron and made into steel pyrite light, brassy yellow greenish black 6-6.5 uneven fracture sources of iron called “fool’s gold”

1b)A student tries to break a mineral apart with their fingernail but is unsuccessful. Using a hammer, they find that it breaks into jagged pieces and leaves a mostly black streak on a ceramic tile Answer: Pyrite (hardness, streak, fracture)

1c) A black mineral leaves a red streak on a streak plate 1c) A black mineral leaves a red streak on a streak plate. When you attempt to break it into pieces it breaks into jagged pieces. Answer: hematite (color, streak, fracture)

1d) A pink mineral leaves a colorless streak and cannot be scratched by glass. Answer: quartz – streak, hardness, color

2) A student finds a colorless mineral but can’t decide whether it is calcite, feldspar or quartz. What one test should she perform to help you figure out which one it is? (Hint: use the chart from the question above to help you answer this Answer: hardness