Unit 4: Minerals and rocks                                                       1   2   3   4

2.1. Classification of minerals

     The main chemical elements that form the composition of minerals

     are: oxygen (O), silicon (Si), aluminium (Al), iron (Fe), calcium (Ca),

     sodium (Na), potassium (K) and magnesium (Mg).

     Other elements exist in very small proportion: carbon, gold,    

     copper, uranium, etc.

     Minerals can be classified by their chemical composition in two

     main groups:

-     Silicates: they are formed by the most frequent elements:

   oxygen and silicon. They are the most abundant minerals

   on the Earth. For example: quartz, feldspar, mica, olivine,

   etc.

-     Non-silicates: they are formed by other compounds and

   do not contain silicon. It can be distinguish several groups:

      Native elements: they are made up of a single element.    

      For example, gold.

      Oxides: They are made up of oxygen and other element.   

      For example, oligiste.

      Sulphides: They are made by sulphur and a metal.

      For example, galena.

      Carbonates They are made up of carbon, oxygen and a metal.

      For example, calcite.

      Halides: They are made up of a metal and chloride or fluoride. 

      For example, halite.

2.6. Diamonds are 100% carbon. Which group of minerals

       do they belong to?  Why?