1. Minerals

2. MINERALS What are minerals? What types of minerals are there? How are minerals formed? Solid/Crystalline Elements or Compounds Naturally Occurring Rock Forming Minerals Ore Minerals Haematite Galena Crystallisation from a Melt Solution (Evaporation) Halite Gypsum Calcite Quartz Micas Feldspars Quartz Feldspar Mica Garnet Calcite Metamorphism (solid state) Garnet Calcite Crystallisation as a cement from flowing pore waters Quartz Calcite Crystallisation from Hydrothermal Fluids in Veins and Faults Gangue Quartz Calcite Ores Haematite Galena Gangue Calcite Quartz

3. How can minerals be identified? Hardness Streak Cleavage/fracture Density/ hefting Lustre Colour Acid Moh’s Scale – fingernail, copper coin, steel nail Powder left on a porcelain tile (colour) Planes of weakness easily broken How heavy it is (by volume) The way a mineral reflects light. Vitreous/Metallic/Glassy/Dull/Transparent/Translu cent Beware – some can show a range of colours HCl will fizz in the presence of CaCO 3 (calcite)

4. Minerals Mineral 1 – black colour, hardness 2.5, one good cleavage plane Mineral 2 – grey colour, scratches streak plate, no cleavage Mineral 3 – white in colour, hardness 6, 2 good cleavage planes in some crystals Mineral 4 – dark green/black in colour, hardness 5-6, 2 good cleavage planes at 90 o Mineral 5 – white in colour, splits along 3 planes Mica Quartz Feldspar Augite Halite or Calcite

5. Minerals Mineral 1 White colour, hardness 6, 2 cleavage planes, vitreous. Mineral 2 Pink colour, hardness 6, 2 cleavage planes, vitreous. Mineral 3 Colourless, scratches streak plate, no cleavage planes, vitreous. Mineral 4 Black colour, scratched by finger nail, 1 cleavage planes.

6. Minerals are Formed by: Crystallisation from a melt Crystalline interlocking texture so rarely euhedral Major minerals – quartz, feldspar, mica

7. Minerals are Formed by: Metamorphic Recrystallisation Crystalline interlocking texture often with overgrowths Major minerals – calcite, garnet

8. Minerals are Formed by: Evaporation Crystalline usually euhedral Major minerals – halite

9. Minerals are Formed by: Crystallisation as cement from flowing pore waters Crystalline very fine grained holds clasts together Major minerals – quartz, calcite

10. Minerals are Formed by: Crystallisation from hydrothermal fluids Crystalline in veins and faults crystallises out from supersaturated fluids when cools Major minerals – gangue, quartz, calcite, ores: haematite, galena