Crystallisation from solution in evaporating
water (halite)
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)
Crystallisation as cement from flowing pore waters (quartz, calcite). As the
water cools, the minerals crystallise out from the fluid
Crystallisation from hydrothermal fluids in veins and faults
(gangue minerals) (quartz, calcite, ore minerals, hematite,
galena)
Metamorphic recrystallisation (calcite,
garnet)
Crystallisation from a melt (quartz,
feldspar, mica)