Page 10 - Curriculum Visions Dynamic Book

Bauxite
Aluminium is found in every handful of soil you hold. It begins
as a part of minerals in rocks such as granite. One of the most common minerals containing aluminium is pink or grey feldspar. To break down the feldspar and make clay, all that nature requires is water, warm weather and a very long period of time.
As rainwater washes over the surface of the feldspar, invisible chemical reactions occur. They are the same reactions that cause limestone statues on buildings to become weathered. The water, often with carbon dioxide gas from the air, rots the feldspar. The result is to release the elements in the feldspar and put them into solution. The aluminium quickly combines with silicon and oxygen to form clay. Because the clay is formed in water, it can no longer be destroyed by future rainfall. This is the secret to how aluminium is locked up in the world’s clays and why it is so difficult to recover it.
The ore containing aluminium, called bauxite, forms in places where the aluminium compounds become especially concentrated.
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 Open cast mining
of bauxite in Jamaica.
The waste rock and soil, called the overburden, is first removed and then the soft bauxite is dug out in large slices before being carried away using dumper-trucks. The overburden is used to fill in the areas already mined of its bauxite. The land can then be reclaimed.