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 <[email protected]> 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, [email protected] > wrote: > > > essage: 3 > > Date: Wed, 30 Mar 2011 12:20:31 -0400 > > From: Michael Gilmer <[email protected]> > > Subject: Re: [meteorite-list] Color of OC's by Staining or by Trace > > Elements > > To: Thunder Stone <[email protected]> > > Cc: [email protected] > > Message-ID: > > <[email protected]> > > 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 <[email protected]> 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. > >> ______________________________________________ > >> Visit the Archives at > >> http://www.meteoritecentral.com/mailing-list-archives.html > >> Meteorite-list mailing list > >> [email protected] > >> http://six.pairlist.net/mailman/listinfo/meteorite-list > >> > > > > > > -- > > > > ----------------------------------------------------------- > 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: [email protected] > > Weblinks: > School of Earth and Space Exploration: http://sese.asu.edu/ > Center for Meteorite Studies: http://meteorites.asu.edu/ > > ----------------------------------------------------------- > > > > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > [email protected] > http://six.pairlist.net/mailman/listinfo/meteorite-list ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
