Earth Sciences 1022A/B Lecture Notes - Lecture 3: Drywall, Sphalerite, Augite
27 Nov 2015
School
Department
Course
Professor
Document Summary
Amethyst a gemstone (it is purple because of impurities) Minerals are solid chemical compounds found in nature. When determining what a mineral ( to tell them apart) is you can . Cleavage (if you whack a hammer onto a mineral it will essentially break in half with the same patterns) There are 4700 minerals discovered (only 20 are really common on earth) Silicates (silicon-oxygen-tetrahedron) (tetra is latin for four . hedron is latin for pyramid) (figure 3. 27 two representations of the silicon-oxygen tetrahedron in the textbook) Olivine single tetrahedral bonded to fe+2, mg+2 ions (figure 2. 23 the classification of common silicate minerals in the textbook illustrates this) Olivine: diagram on phone (olivine does not have a cleavage) (but it does vary from composition from one extreme to another) Pyroxene: single chains of tetrahedral, ~90 angle cleavage. Biotite: (black mica) tetrahedral sheets with perfect (basal) cleavage (figure 3. 28 cleavage angles for augite and hornblende illustrates these)
