[meteorite-list] Meteorites delivered Earth's gold

[Chris Peterson]

Quartz formed in the Earth's crust, and stayed there. It is light 
(compared with gold) and doesn't have an affinity for iron. Indeed, it 
continues to form, given the abundance of silicon and oxygen in the 
crust and mantle. In bulk, there is no more gold in meteorites than in 
the Earth. The Earth is simply more differentiated, and most of its 
original gold is now in the core. What this paper proposes is that 
meteorites were the source of gold (and possibly other elements) that we 
find in surface material, since these elements were introduced after the 
Earth differentiated.

Nothing changed meteorites (in the sense I think you mean), and we don't 
find solid gold meteorites because gold is a trace element, and there 
was no mechanism to concentrate it.

Chris

*******************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 9/10/2011 3:36 PM, cdtucson at cox.net wrote:
> Paul, List,
> It seems to me that much of the Gold found on Earth is accompanied by Quartz.  In fact most of the finest Non-nugget specimens are usually found in quartz.
> That said; If this gold came from space then where did the quartz come from and for that matter why is gold not found buried in chonditic rock instead of quartz. . Quartz does not seem to be terribly abundant in meteorites.
> Just curious why we don't find gold / quartz meteorites. What changed meteorites? Do we have any witnessed falls of Gold meteorites?
> Do these researchers consider the Quartz issue here?
> Thanks.
> Carl