Friday, September 02, 2011

What About Silicon

What About Silicon? 


Silicon is the second most common element in the earth's crust, with oxygen being number one.  This means man has figured out how to use it to our advantage.  We use it for abrasives, making glass, silicon chips for computers, in grease and caulking.

Oddly, it is not naturally found in or incorporated into our bodies, which is surprising given its abundance.  Because silicon is so closely related to carbon (the next element in the periodic table),science fiction writers have speculated relentlessly about life forms made of pure silicon from other planets.  Indianaa Jones and the Kingdom of the Crystal Skull made hype of this.  I love the scene where he says the skull was carved from a single piece of silicon, against the grain. Indiana says ," ...even today we couldn't cut a piece of quartz like that without it exploding."  I think he means HE couldn't do it.  Even though some forms of quartz do show grain, I know we can polish it here at the rock shop without anything exploding.  Most agates (banded chalcedony) do have a grain to them.  But in the movie it was clear quartz that the skull was made of and large pieces of clear quartz crystals tend to not have a grain.  If you do any tumbling or polishing of rocks you know you can polish against the grain without any explosions!

Silicon easily bonds with oxygen to form a tetrahedral molecule called silicate.  This silicate by itself is called quartz.  When the silicate molecule bonds with sodium or potassium it forms feldspar minerals.  When it bonds with iron/manganese it can form garnets.  When it bonds with beryllium it forms aquamarine/red beryl/emeralds/goshenite.  The list goes on and on to as there are hundreds of silicate minerals.  See Mindat.org for a complete list.

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