06.Periodicity of Behavior;
       Sodium Through Argon
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       Framework of the Planets: Silicates VI

Feldspars are silicates in which one fourth to one half of the Si4+ ions in the tetrahedra have been replaced by Al3+, thereby requiring one additional +1 charge from a positive ion for each such substitution.

Since feldspars are open, three-dimensional cage structures, they are lighter than pyroxenes and olivine. In the original stratification of the planet, feldspars floated to the top, and today make up 60% of the crust of the Earth by weight.

Quartz, which also is light, is responsible for another 12%. Micas and clays contribute 5%, the heavier pyroxenes 12%, and dense olivine only 3% of the crust, with the last 8% being iron oxides and miscellaneous minerals.

Granite, probably the most familiar of all rocks, is a mixture of fine crystals of quartz, feldspar, and mica.

It is interesting to reflect that all of this silicate geology arose because silicon cannot make double bonds with oxygen.


If by some cosmic readjustment, the size of a silicon atom were to decrease by 25 %, then such a double bond would become possible.

All of the silicates in our planet would boil away in clouds of SiO2, gas, leaving behind only a metallic core of half the present radius, covered by a scum of metal oxides.

It is easy to see why the "fitness of the worId" was used by theologians of the past century as a scientific demonstration of the existence of a Designer in the universe.

The "fitness" of carbon and silicon for the separate roles they play on our planet is uncanny.

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