[meteorite-list] Color of OC's by Staining or by Trace Elements

From: Count Deiro <countdeiro_at_meteoritecentral.com>
Date: Thu, 31 Mar 2011 08:03:43 -0700 (GMT-07:00)
Message-ID: <13865130.1301583823793.JavaMail.root_at_elwamui-rubis.atl.sa.earthlink.net>

Thank you, Dr. Garvie.

Very useful and concise.

Count Deiro
IMCA 3536


-----Original Message-----
>From: Laurence Garvie <lgarvie at asu.edu>
>Sent: Mar 30, 2011 11:30 PM
>To: "meteorite-list at meteoritecentral.com" <meteorite-list at meteoritecentral.com>
>Subject: [meteorite-list] Color of OC's by Staining or by Trace Elements
>
>Just a quick reply to this subject as it could become lengthy and involved.
>
>The primary coloring agent in meteorites is Fe2+ for fresh meteorites and Fe3+ for weathered ones (BTW - shocked meteorites can be black - see below). There is also Fe0, which is in the metal.
>
>When a few percent of Fe2+ is present, then minerals such as pyroxenes and olivines are usually green to greenish-yellow. A good example of Fe2+ coloring is in Johnstown, which is composed primarily of green pyroxene.
>
>If very little Fe2+ is present then pyroxene is normally white/clear as in the aubrites, such as Bishopville.
>
>In our oxidizing atmosphere, the metals in meteorites rust, producing Fe3+ -bearing oxides/oxyhydroxides. These rust minerals stain the meteorite and can range in color from yellow-orange-red-purple-brown-black.
>
>Shocked meteorites can be black. A great comparison is between the two know chassignites - Chassigny and NWA2737, both of which have similar mineralogies. Fresh Chassigny is yellowish green - the color is caused by Fe2+ in the olivine. Yet, NWA2737 is black. The black color is caused by abundant 5 to 15 nanometer-sized iron-nickel droplets in the olivine, which are strongly absorbing in the visible and near-IR region of the spectrum. These droplets are formed during intense shock events.
>
>Practically everything you ever wanted to know about color in minerals can be found at Prof. Rossman's site at http://minerals.gps.caltech.edu/
>
>
>Laurence
>CMS
>ASU
>
>On Mar 30, 2011, at 7:52 PM, meteorite-list-request at meteoritecentral.com wrote:
>
>> essage: 3
>> Date: Wed, 30 Mar 2011 12:20:31 -0400
>> From: Michael Gilmer <meteoritemike at gmail.com>
>> Subject: Re: [meteorite-list] Color of OC's by Staining or by Trace
>> Elements
>> To: Thunder Stone <stanleygregr at hotmail.com>
>> Cc: meteorite-list at meteoritecentral.com
>> Message-ID:
>> <AANLkTin9FfUsroBhMrVFDfH1_GCoss3B3L-vFf9zJ6T_ at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Hi Greg and List,
>>
>> Great question Greg. I'm curious to hear what the experts have to say.
>>
>> Some OC's start out as white or light-grey - like some LL6 types.
>> That is why some LL6 meteorites are mistaken for lunars or eucrites -
>> because they lack chondrules and have that whitish color.
>>
>> Best regards,
>>
>> MikeG
>>
>> ----------------------------------------------------------------------
>> Mike Gilmer - Galactic Stone & Ironworks Meteorites
>>
>> Website - http://www.galactic-stone.com
>> Facebook - http://www.facebook.com/galacticstone
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>> EOM - http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564
>> -----------------------------------------------------------------------
>>
>>
>>
>> On 3/30/11, Thunder Stone <stanleygregr at hotmail.com> wrote:
>>>
>>> Hi List:
>>> I hope everyone is well.
>>> I have a question regarding the 'color' of OC's through staining by some
>>> mineral influx or by oxidation. It appears most fresh OC's start out as a
>>> light beige or tan color; then through time the metal rusts and they often
>>> turn yellowish, orange, or brownish - this make sense. My questions is
>>> this:
>>> What other colors can they become, blue or green? What element(s) result in
>>> different colors? What different weathering processes are involved?
>>> The reason I ask is because I have a weathered meteorite that is dark green
>>> in color; it looks like jade and I have not seen any like this one before.
>>> I have also and seen OC's with a 'black' color, what causes that?
>>> Thanks,
>>> Greg S.
>>> ______________________________________________
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>>
>>
>> --
>>
>
>-----------------------------------------------------------
>Dr. Laurence A.J. Garvie
>Collections Manager
>Center for Meteorite Studies
>School of Earth and Space Exploration
>Arizona State University
>Tempe
>AZ 85287-1404
>USA
>
>phone: 480 965 3361
>fax: 480 965 8102
>email: lgarvie at asu.edu
>
>Weblinks:
>School of Earth and Space Exploration: http://sese.asu.edu/
>Center for Meteorite Studies: http://meteorites.asu.edu/
>
>-----------------------------------------------------------
>
>
>
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Received on Thu 31 Mar 2011 11:03:43 AM PDT