[meteorite-list] NWA 1109 Howardite or Eucrite?

From: Adam Hupe <adamhupe_at_meteoritecentral.com>
Date: Thu Apr 22 10:07:00 2004
Message-ID: <002001c27255$aaf27c00$f60ee70c_at_attbi.com>

Dear list members,

Here is the most up to date information I have on NWA 1109. I just finished
reviewing this today. This is provisional data and should not be
reproduced. A final will be submitted soon to the Nomenclature Committee
for vote and, hopefully, final approval to make this meteorite official. I
guess I should not have over simplified the 10% versus 90% ratio. It has
clearly caused some confusion. This is why I referenced Dave Weir's web
site that addresses this issue in easy to understand terms. As far as NWA
1109 is concerned, I was surprised to read, has no orthopyroxene or
chondritic component at all, just an interesting batch of accessory
minerals. Some corrections on this report need to be made on the number of
stones and total known weight but everything else is accurate. I hope this
helps to clear things up on NWA 1109.


Northwest Africa 1109
 Morocco
 Purchased 2001 October/December
 Polymict eucrite breccia
A. and G. Hupé (Hupé) purchased three stones totaling 860 g from a Moroccan
dealer in 2001 October and December, but the total estimated weight of this
material including that held by other collectors is estimated to be 2.5 kg.
The stones have an overall light tan to pale brown color depending on extent
of weathering, but all show distinctive white and grey mineral and lithic
clasts in a light tan matrix Classification and mineralogy (A. Irving and
S. Kuehner, UWS): Polycrystalline clasts include basaltic eucrites (ophitic
texture, variable grainsize, mainly anorthite+pigeonite Wo16Fs57, FeO/MnO =
30), cumulate eucrites (coarse grained, equigranular, mainly
anorthite+exsolved pigeonite with accessory silica), rare eucritic breccias,
and distinctive ferroan intergrowths (very fine-grained, "eutectoid"
aggregates of intergrown fayalite+hedenbergite+silica+troilite, which appear
to be quenched igneous mesostasis; some examples are associated with
anorthite phenocrysts, and others appear to have partially replaced exsolved
pigeonite grains). Mineral clasts include homogeneous pigeonite grains
(e.g., Wo15Fs31, FeO/MnO = 26), pigeonite grains with clinopyroxene
exsolution lamellae (FeO/MnO = 30-33), anorthite and a silica polymorph.
Orthopyroxene typical of diogenites was searched for but not found (thus
this sample is not a howardite). Accessory minerals in clasts and matrix
include ilmenite, Ni-free Fe metal, chromite, baddeleyite and apatite.
Specimens: type specimen, 50 g, and four polished thin sections, UWS; main
mass, Hupé.

All the best,

Adam
Received on Sat 12 Oct 2002 09:12:57 PM PDT