1. CEE 437 Lecture 2 Minerals Thomas Doe

2. Topics Mineral Definition Rock Forming Minerals Physical Proprieties of Minerals Mineral Identification Mineral Lab

3. Mineral Definition Naturally occurring material with unique combination of chemical composition and crystalline structure Natural non-minerals — glasses, coal, amorphous silica Pseudomorphs: diamond:graphite

4. Galena, PbS Graphite, C

5. Crystalline Symmetry Groups

6. Crystal Forms, Cubic System

7. Crustal Composition

8. Differentiation of Crustal Composition Weathering differentiating towards higher Silica Preferential melting of higher silica Concentration of C, Ca, Na, K in sea and air Original basaltic composition of crust Carbonate concentrated by organic processes

9. Mineral Differentiation Plate tectonics –selective melting, selective recrytallization –differentiation by density Weathering and erosion

10. Elemental Fates Silicon tends to concentrate in crust — quartz is very long lived Aluminum — transforms from feldspars to clays Mica — transform to clays Fe-Mg-Ca-Na-K concentrate in some clays and micas, concentrate in oceans in biosphere

11. Rock Forming Minerals Composition of Crust –Dominantly O, Si, Fe, Mg, Ca, Na, K –Near surface importance of bio-processes –Silicates from inorganic processes –Carbonates mainly from shell-forming organisms

12. Major Silicate Groups Silicon Tetrahedron –separate tetraheadra — olivine –single chains — pyroxene –double chains — amphibole –sheet silicates — micas and clays –framework silicates — feldspars (with Al substitution), quartz as pure silica

13. Forms of Silicates

15. Crystalline Structure of Calcite

16. Physical Properties Density (Gravity) Electrical Conductivity (Resisitivity) Thermal Expansion Strength Elasticity (Mechanical properties, –Seismic/Acoustic Velocity Rheology (Plasticity,Viscosity)

17. Deformation Mechanisms

18. Effects on Physical Properties Anisotropy –Properties differ by direction Heterogeneity –Properties vary by location Mineral properties may have strong anisotropy when crystals are aligned Heterogeneity may have strong mechanical effects when different minerals have different deformation properties

19. Clay Viewed from Electron Microscope

20. Mineral Identification Density Hardness Color, luster (metallic, non-metalic, semi- metallic) Crystalline habit Cleavage Mineral chemistry, x-ray diffraction

21. Hardness Scale

22. X-Ray Diffraction Bragg’s Law