[meteorite-list] REport: Minerals in Allende Meteorite

From: MARK BOSTICK <thebigcollector_at_meteoritecentral.com>
Date: Mon Mar 28 16:57:20 2005
Message-ID: <BAY104-F242D318BD139BC9CC722D7B3440_at_phx.gbl>

Your welcome Harlan,

My original post did not go through, so for benifit of the group I am
reposting. I think this gives a very good, not too technical answer to what
is in Allende.

Smithsonian Contributions to the Earth Sciences
SCES-5, The Allende, Mexico, Meteorite Shower

Roy S. Clarke, Jr., Eugene Jarosewich, Brian Mason, Joseph Nelen, Manuel
Gomez and Jack R. Hyde

Issue Date: February 17, 1971

"Chemical and mineralogical compositions establish that Allende is a Type
III carbonaceous chondrite. Three distinct components can be recognized:
finegrained black matrix (~60%), chondrules (~30%), and irregular white
aggregates (~10%). The matrix consists almost entirely of iron-rich olivine
(average 50% Fe2SiO4), with minor amounts of troilite, pentlandite, and
taenite, rendered opaque by dispersed carbonaceous material. Most of the
chondrules are magnesium-rich, and consist of olivine (average 9% Fe2SiO4)
with minor amounts of clinoenstatite and some glass; a few chondrules are
rich in calcium and aluminum, and are made up largely of anorthite,
gehlenite, augite, and spinel. The irregular aggregates are also rich in
calcium and aluminum, and contain anorthite, gehlenite, augite, spinel,
nepheline, grossular, and sodalite (the last two minerals have not
previously been recorded from meteorites). Complete chemical analyses have
been made of the bulk meteorite, a dark inclusion, the matrix, a chondrule
concentrate, two individual chondrules, and a single aggregate."

Clear Skies,
Mark Bostick
www.meteoritearticles.com
Received on Mon 28 Mar 2005 04:57:18 PM PST