1. Important Non-Silicates

2. Hematite-Corundum Ilmenite FeTiO 3 is similar

3. Halite and Galena

4. Pyrite

5. Diamond

7. Sphalerite

8. Chalcopyrite

9. Halite and Calcite

10. Calcite

11. Fluorite Uraninite UO 2 is isostructural

12. Goethite

15. Lepidocrocite

17. Bauxite and Limonite Bauxite MineralsLimonite Minerals Gibbsite Al(OH) 3 Boehmite AlO(OH)Lepidocrocite FeO(OH) Diaspore AlO(OH)Goethite FeO(OH)

18. Perovskite

19. Perovskite in the Mantle Perovskite is CaTiO 3 Enstatite (Mg Pyroxene) = MgSiO 3 Can collapse to perovskite structure at high pressure

20. Rutile

22. Cassiterite SnO 2 is isostructural

23. The Spinels AB 2 O 4 A is divalent, B is trivalent Oxygens in cubic close-packed structure In a close-packed structure, there is one octahedral site for every oxygen and two tetrahedral Ideally B occupies half of octahedral sites and A occupies 1/8 of tetrahedral sites

24. Normal and Inverse Spinels In normal spinels, B (trivalent) occupies octahedral sites and A (divalent) occupies tetrahedral sites In inverse spinels, A (divalent) occupies octahedral sites and B (trivalent) occupies tetrahedral sites In real spinels there is a lot of crossover

25. Important Spinels Spinel (normal) MgAl 2 O 4 Hercynite (normal) FeAl 2 O 4 Magnetite (inverse) Fe ++ Fe +++ 2 O 4 Chromite (inverse) FeCr 2 O 4 Ulvospinel (inverse) Fe 2 TiO 4 Franklinite (inverse) ZnFe +++ 2 O 4 Maghemite (inverse) Fe 2 O 3

26. Spinel

30. Spinel in the Mantle Spinel = AB 2 O 4 Forsterite (Mg olivine) = Mg 2 SiO 4 Can collapse to SiMg 2 O 4 at high pressure Si in octahedral sites, not tetrahedral!