1. Silicates SiO n silicon oxide  1/3 of all minerals are silicates  about 95% of the Earth’s crust is composed of silicates

2. Earth’s Crust Chemical Composition ELEMENTWEIGHT% O (oxygen) 47 Si (silicon) 28 Aluminum 8 Fe (iron) 5 Ca (calcium) 4 Na (sodium) 3 K (potassium)3 Mg (magnesium) 2 Total 98.5%

3. Average Mineral Crustal Composition Mineral Weight% feldspar * 66 * quartz * 10 * magnetite/hematite 6 Ferromagnesium minerals * (olivine, pyroxene, amphibole, biotite) 15 * Total 97 *silicate

4. Other important minerals muscovite (mica) gypsum clays halite calcite dolomite

7. MINERAL IDENTIFICATION Primarily based on physical properties.

8. The properties of each mineral are determined by: chemical elements present arrangement of elements in the mineral structure

10.  Streak (scratchability) Color of powdered mineral

11. Specific gravity Au gold PbS galena Density - mass/volume Specific gravity - mass of sample / mass of equal volume of water

12. Cleavage planar surfaces caused by breaks along planes of weakness in atomic structure. Number of directions and angle important.

13. Cleavage

14. cleavage

15. Cleavage

17.  Fracture Irregular surfaces caused by breaks

18.  Crystal form External morphology due to atomic structure. Quartz and corundum have 6 crystal faces.

19. Luster The way in which light is reflected, e.g., metallic, glassy

20.  Color Poor except for metallics and silicate varieties

21. Hardness Mohs Hardness Scale 1. Talc 2. Gypsum 2.5finger nail 3.5penny 3. Calcite 4. Fluorite 5. Apatite 5.0 nail 5.0-6.0 glass and knife blade

22. 6. Orthoclase (feldspar) 7. Quartz 8. Topaz 9. Corundun 10. Diamond

23. Striations odor magnetic Double Refraction

24. Mineral Resources Ore -- mineral that can be mined for a profit Gangue­­--worthless minerals in an ore body

25. examples of ores Ag silver Au gold Copper sulfides (covellite) Feoxides (hematite) PbS lead sulfide (galena) The U.S.A imports about 80% of the most used 16 metals!