Elemental abundances in the crust

Elemental abundances in the crust - Elemental abundances in...

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Elemental abundances in the crust. O Si Al Fe Ca Na K Mg H % wt 46.6 27.7 8.1 5.0 3.6 0.8 2.6 2.1 0.14 Classifying minerals A Mineral is a naturally occurring substance which consists of a conglomeration of crystals - individual crystals being called "grains". The size of the grains tells you much about the environment in which the crystals formed: small grains indicate cooling was rapid (e.g lava - surface cooled magma - has no evidence of structure at all), large that it cooled slowly, giving time for the crystals to build in size. Classifying minerals can be done on erals can be done on a number of ways. One is by the number of oxygen atoms contained per molecule. That is, take ratio: (No. of metal atoms)/(No. of oxygen atoms) Four ratios cover most of the common minerals: 12/24; 15/24; 16/24 and 18/24, that is, 1/2, 5/8, 2/3 and 3/4. The 1/2 ratio is represented largely by Silica, SiO 2 The 5/8 minerals include Feldspars MM'AlSi 2 O 8 where M can be K, Na or Ca and M' Si or Al (Ca and Al tend to go together).
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Elemental abundances in the crust - Elemental abundances in...

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