1. Mineral formation

2. Warm-up What factors affect how a mineral forms?
How long do you think it takes to form a crystal?

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

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

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

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

7. 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

8. Factors that affect crystal growth
Size/shape of environment
Temperature
Pressure
Seed crystal

10. Size of environment
Bigger the space, bigger the crystal

11. Temperature
Longer it takes to cool (stays warm longer) the bigger the crystals can get

12. Pressure
Changes shape/ alignment of crystals

13. Seed crystals
Allows for a “blueprint” for crystal growth