Dichotomous Key for Minerals
1. What is the luster of your mineral?
a. Metallic = Go to 2
b. Nonmetallic = Go to 3
2. What is the color of streak your mineral makes?
a. Red to brown = Hematite
b. Black, grey, or green = Go to 4
3. What is the hardness of the mineral?
a. Less than or equal to 3 = Go to 7
b. Greater than 3 = Go to 9
4. Does the mineral display cubic cleavage (breaks at 90 degress)?
a. Yes = Galena
b. No = Go to 5
5. Is it attracted to a magnet?
a. Yes = Magnetite
b. No = Go to 6
6. Is the mineral harder than a penny (3)?
a. Yes = Pyrite
b. No = Graphite
7. Does the mineral look like it is made of thin flexible sheets?
a. Yes = Go to 8
b. No = Calcite
8. Is the mineral black or almost black?
a. Yes = Biotite Mica
b. No = Muscovite Mica
9. Does the mineral display cleavage?
a. Yes = Go to 10
b. No = Quartz
10. Does the mineral look green (possibly with purple streaks)?
a. Yes = Flourite
b. No = Feldspar
Non-metallic Luster, Light Colored: Shows cleavage
Halite: Colorless to white. Salty taste. Cubic crystals. 3 cleavage planes. Very soluble
Calcite: White to colorless or yellow. Hardness: 3. Bubbles with acid.
Gypsum: White to transparent. Hardness: 2. Glassy to earthy luster. Used in Plaster
Non-metallic Luster, Dark Colored: Scratches glass, Shows cleavage
Amphibole: Black or dark green. Glassy luster. Hardness: 5-6. Common deep in the
Pyroxene: Black or dark green. Glassy luster. Hardness: 5-6. Two cleavage planes at