[Rockhounds] Source of heavy elements in crust?

[Rik Dillen]

If you look carefully enough, I bet you will find any of the 91 more or less stable elements in any meteorite or other
sample (except perhaps for technetium), at least some atoms :>)).
By "looking carefully" I mean analyzing down to something like a few ppq (part per quadrillion), or 0.000 000 000 000 1
%. In some cases that is possible with vey specialized techniques, such as neutron activation analysis or high
resolution ICP mass spectrometry.

We (R. Van Tassel, R. Vochten, E. De Grave, J. Hertogen and myself) determined e.g. Ir (iridium) and Au (gold) in a
fragment of the Santa Catharina meteorite (article appeared in "Meteoritics" about 15 years ago - honestly I wrote first
" a few years ago", until I realized that it was somewhere in 1992). Actually we found 0.03 ppm (0.000 003 %) Ir and 3.3
ppm (0.00033 %) Au.

So I can confirm from our own measurements that precious metals have been found (or rather "detected") in meteorites.
Grts,

Rik DILLEN 
Doornstraat 15,  B-9170 Sint-Gillis-Waas 
Belgium 
E-mail rik.dillen at skynet.be 
Homepage : http://users.skynet.be/rik.dillen 
 

-----Original Message-----
From: rockhounds-bounces at lists.drizzle.com [mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Alan Goldstein
Sent: Monday, September 22, 2008 10:01 PM
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
Subject: Re: [Rockhounds] Source of heavy elements in crust?

It would be a safe bet to say the geology of Earth is a reflection of the 
composition of the formation of the Solar System. Whether precious metals 
were accumulated during the initial collision of planetesimals or the rain 
of meteorites during the first billion years of the Earth's history doesn't 
rate among the more pressing issues of geology for me. Have any precious 
metals been found in any meteorite? They are "precious" because of their 
scarcity. Since meteorites are relatively scarce as well, one would expect 
"scarce squared" would indicate that you are not likely to find gold, 
silver, etc. in meteorites.

On a related matter, geologists say that earth's oceans are from comets 
colliding with our planet.

Alan


----- Original Message ----- 
From: "J Bryan Kramer" <codeburner at gmail.com>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" 
<rockhounds at lists.drizzle.com>
Sent: Monday, September 22, 2008 10:36 AM
Subject: [Rockhounds] Source of heavy elements in crust?


This fellow thinks the crust was seeded with  heavy elements from meteor
strikes 4 GYa

<
http://www.universetoday.com/2008/09/22/earths-precious-metals-could-be-from-meteorites-and-asteroids/
>

BK 


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