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Notes on

How Minerals Form


What is a geode?






What is crystallization?




What are the two methods that cause minerals to form?











A geode is a rounded hollow rock that is lined with mineral crystals.  This occurs because water with chemicals seeps into a crack in a rock and minerals form over time.


Crystallization is a process by which atoms are arranged to form crystals.



They can form by crystallization of magma

  • When magma cools and then hardens minerals will form
  • If it cools deep within the earth it takes longer to cool and larger minerals will form.
  • If it cools at the earth’s surface it cools faster and smaller crystals or no crystals will form.


They can form by crystallization of a solution

  • A solution is a mixture when one substance is dissolved in water
  • There are two ways in which minerals form from solutions
  •  --They can form by evaporation of solutions – this usually occurs at the edges of oceans (salts)
  • --They can form from how water solutions that cool – This usually occurs in underground caves

--veins – are narrow channels in which hot water solutions seep in.