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

From: cdtucson at cox.net <*cdtucson_at_meteoritecentral.com*> Date: Sat, 2 Apr 2011 13:20:11 -0400 Message-ID: <20110402132011.SXFJY.292880.imail_at_fed1rmwml35> · cdtucson_at_meteoritecentral.com

--
Carl or Debbie Esparza
Meteoritemax
---- Alan Rubin <aerubin at ucla.edu> wrote: 
> There are a lot of so-called black chondrites, including Farmington.  These 
> are due to small particles of metal and sulfide having been shock-injected 
> into the mafic silicates, in a process that I have called silicate darkening 
> and others have called shock blackening.
> 
> Alan
> 
> 
> Alan Rubin
> Institute of Geophysics and Planetary Physics
> University of California
> 3845 Slichter Hall
> 603 Charles Young Dr. E
> Los Angeles, CA  90095-1567
> phone: 310-825-3202
> e-mail: aerubin at ucla.edu
> website: http://cosmochemists.igpp.ucla.edu/Rubin.html
> 
> 
> ----- Original Message ----- 
> From: <cdtucson at cox.net>
> To: "Laurence Garvie" <lgarvie at asu.edu>; 
> <meteorite-list at meteoritecentral.com>
> Sent: Thursday, March 31, 2011 2:30 PM
> Subject: Re: [meteorite-list] Color of OC's by Staining or by Trace Elements
> 
> 
> > Laurence,
> > I have a question.
> > You said;
> > "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."
> >
> > I googled this subject and found that the only time this was the case so 
> > far is in this exact Martian meteorite.
> > I can find no other reference where an Olivine is visually black in color.
> > So, does this mean that black olivine is definitive of meteoritic olivine?
> > I mean if you find a black rock ( dunite)  that you suspect is a meteorite 
> > , and a PTS or microprobe reveals it to in fact be olivine. Does this mean 
> > it is a meteorite?
> > What seems equally as amazing is that this is the only olivine ever 
> > verified that is black including all of the ones from earth.
> > This NWA 2737 truly is beautiful. Carine and Bruno still had some left at 
> > the recent Tucson show.  I have seen and held it many times. It is solid 
> > black.
> > Thanks,
> > Carl
> >
> >
> > --
> > Carl or Debbie Esparza
> > Meteoritemax
> >
> >
> > ---- Laurence Garvie <lgarvie at asu.edu> wrote:
> >> 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
> >> > News Feed - http://www.galactic-stone.com/rss/126516
> >> > Twitter - http://twitter.com/galacticstone
> >> > 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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