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Re: Geo vs Astro chemistry was Asteroid, Comet, etc. question

Hi Troy, Elton and list
I just wanted to clear up a few of the points that Elton stated in his 
excellent post to Troy Bell.
Elton wrote the following:
Snip
Troy wrote:
 Hi list, I am confused about something.  Given the vast different elements 
here
on earth, some 100+, I ask this question. I would expect that other
planets/asteroids/comets would be made up of those other elements or even some
new elements and not necessarily nickle/iron. 

 Q: Why is it that one of the main tests for meteorites is the nickle/iron
content in them?

A:  Iron and Nickel can rarely be found together on earth.... rarely is iron
found in "native" form but when it is, it is product of human industry.   
Matter of factly-- I don't think you will ever find native (pure)iron from a
natural source on earth.  Any time you find it it on the earth it will be from
human activities OR extra-terresterial.  
Snip

I believe rarely is the key word here.  I have native iron from two different 
locations and each sample cost much more than a typical iron meteorite.  Here 
are a number of references for the location of native iron. 

(1)Anthony et al.  Handbook of Mineralogy Vol 1 Elements Sulfides Sulfosalts, 
1990
p241 Iron.

Distribution: In Greenland, at Fortune Bay, Mellemford, Asuk, and elswhere on 
the west coast; Disko Island, near Uivfaq and Kitdlit.  From Ben Bhreck, 
Scotland.  At Buhl, near Weimar, Hesse, Germany. In Poland, near Rouno, Wolyn 
district. In the USSR at Grushersk, in the Don district and from the Hatanga 
region, Siberia.  In the USA, at Cameron, Clinton Co., Missouri; and near New 
Brunswick, Somerset Co., New Jersey.  In Ontario, Canada, in Cameron 
Township, Nipissing district; and on St. Joseph Island, Lake Huron.  Noted in 
small amounts at a number of additional localities.

There are also several localities for native nickel from ref (1) p349.
Distribution: From Bogota, near Canala, New Caledonia.  In the Jerry River, 
in placers derived from Red Hills Range, southern Westland, New Zealand. From 
Mount Clifford and Cutmore, near Agnew, Western Australia and the Nairne 
pyrite deposit, South Australia.  At Kaltenberg, Turtmauntal, Valais, 
Switzerland.  On Grasshopper Mountain, Tulameen, British Columbia, Canada

While there are numerous locations for both nickel and iron please remember 
that even at these locations it is fairly uncommon.  I have collected 
minerals for 20 years and only have one nickel locality and two different 
iron localities.

Snip
Iron-nickel is a "signature" for meteorites because it distinguishes it from
iron from human sources. On Earth, nickel can be found in native crystalline
form but will not be found in a native mixture with iron. 
Snip

This statement is a little misleading.  Again very rarely nickel and iron can 
be found together on earth.
Here is the chemical analysis from the iron from Blaajfeld, Greenland from 
the same reference as above.
Fe 93.16
Ni   2.01
Co  0.80
Cu  0.12
C    2.34
P    0.32
S    0.41
Cl   0.02
Tot 99.18

There is also another interesting chemical analysis from the Jerry River, New 
Zealand nickel location listed above.
Ni 96.30
Fe  1.77
Co  0.69
Tot 98.76

Again I would like to restate that Elton presented an excellent post.  I just 
wanted to clear up a few minor errors.  Please remember that all of these 
locations for native iron and nickel are quite rare but must always be 
considered when testing for meteorites.  Additionally Elton stated that 99.9% 
of the time when iron meteorites test positive for nickel they will be a 
meteorite.  I would agree with that statement.  Most of the above localities 
you would not confuse them with an iron meteorite but you could easily 
confuse them with a stony meteorite.  More on that in the next post.
Mike Jensen
Jensen Meteorites

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