Minerals are formed by

Minerals are formed by

1. Crystallisation from solution in evaporating water (halite)

2. Minerals can be valuable if they contain metals (ores: haematite, galena, gold) or have properties such as being rare, hard, lustrous and/or coloured that cause them to become precious or semi-precious stones (quartz (amethyst), diamond)

3. Crystallisation as cement from flowing pore waters (quartz, calcite). As the water cools, the minerals crystallise out from the fluid

4. Crystallisation from hydrothermal fluids in veins and faults (gangue minerals) (quartz, calcite, ore minerals, hematite, galena)

5. Metamorphic recrystallisation (calcite, garnet)

6. Crystallisation from a melt (quartz, feldspar, mica)

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