Unit 2 Minerals Rocks and Minerals

Common rock-forming minerals There are almost 3000 types of minerals, but only 8 of these minerals make up 90% of the rocks of Earth’s crust. 1. Quartz 12% 2. Potassium Feldspar 12% 3. Plagioclase Feldspar 38% 4. Pyroxene 11% 5. Hornblende/Amphibole 5% 6. Biotite Mica 5% 7. Clays 4.6% 8. Olivine 3%

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