1. Mineralogy Minerals and crystals

2. World’s largest crystals: A cave in the Naica Lead Zinc mine, Mexico

3. Miners in Cueva de los Crystals: the mineral gypsum Crystals of a variety of gypsum (CaSO 4.2H 2 O) precipitated from hot water at 60 degrees celsius in a limestone cave in the Naica mine

4. Minerals Tourmaline on Feldspar Emerald Beryl (Be 3 Al 2 (SiO 3 ) 6

5. Crystal Shapes Halite (NaCl) Diamond (C) Quartz (SiO 2 ) Garnet (Fe 3 Al 2 Si 3 O 12 ) Stibnite (Sb 2 S 3 ) Calcite (CaCO 3 )

6. Pyrite (FeS 2 ) crystals

7. Feldspars – two of the most important rock-forming minerals Plagioclase Albite – NaAlSi 3 O 8 Anorthite CaAl 2 Si 2 O 8 K-feldspar KAlSi 3 O 8 Microcline Orthoclase Sanidine

8. Colours and forms of quartz Milky quartz Rose quartz Amethyst Citrine

9. Quartz crystals displaying prism and pyramid faces

10. Faces display consistent angular relationships Quartz Crystal Angles measured with a goniometer Prism Pyramid

11. Crystals have ordered arrangements of atoms Order Disorder

12. X-ray beam splits into numerous smaller beams. Interference of waves of different beams produces a diffraction pattern on a screen or film. The pattern indicates the spacing and arrangement of atoms. X-ray diffraction

13. Surface of galena (PbS) imaged With an atomic force microscope Atomic structure of galena (PbS) Sulphur Lead

14. The atomic structure of halite (NaCl) Ionic bonding

15. Ionic bonding – transfer of electrons Cation + Anion -

16. Relative sizes of ions Ion co-ordination

17. The atomic structure of diamond Covalent bonding

18. The source of Diamonds Kimberlite containing diamond The ‘Big Hole’ at Kimberly, South Africa

19. Cutting diamonds

20. Covalent bonding – sharing of electrons

21. Atomic structure of graphite Covalent bonding within sheet Van der Waal’s bonding between sheets

22. Ice Crystals Hydrogen bonding

23. The silicon tetrahedron

24. Silicate Structures Inosilicate (Single chain) Sheet silicate Nesosilicate (Double chain) Framework silicate SiO 4 4 - SiO 3 2- Si 4 O 10 4 - SiO 2 Si 4 O 11 6 -

25. (Fe,Mg) 2 SiO 4 Nesosilicate Olivine

26. Diopside CaMgSi 2 O 6 Hypersthene (Fe,Mg)SiO 3 Inosilicate (Single Chain) Pyroxene

27. Inosilicate (Double Chain) Amphibole Tremolite Ca 2 Mg 5 Si 8 O 22 (OH) 2 Riebeckite Na 2 Fe 5 Si 8 O 22( OH) 2 Tigers Eye

28. Sheet Silicate Biotite KAl(Fe,Mg) 3 Si 3 O 10 (OH) 2 Muscovite KAl 3 Si 3 O 10 (OH) 2

29. Asbestos Uses and risks (Insulation, heat, fire resistance) Serpentine (Mg 3 Si 2 O 5 (OH) 4 Chrysotile (Mg 3 Si 2 O 5 (OH) 4

30. Framework Silicate Quartz SiO 2 Plagioclase Albite NaAlSi 3 O 8 Anorthite CaAl 2 Si 2 O 8 K-feldspar KAlSi 3 O 8 Amethyst SiO 2

31. Relationship of Quartz structure to Feldspar Structure Imagine four SiO 2 molecules 4 x SiO 2 = Si 4 O 8 Substitute Al 3+ for Si 4+ in one of these molecules SiO 2 +AlO 2 +SiO 2 +SiO 2 = AlSi 3 O 8 - Add Na + or K + to supply missing charge = NaAlSi 3 O 8 or KAlSi 3 O 8 SiO 2 +AlO 2 + SiO 2 = Al 2 Si 2 O 8 2- Add Ca 2+ to supply missing charge = CaAl 2 Si 2 O 8 Albite K-Feldspar Anorthite