Meteorite: NWA 7831 HED Achondrite Diogenite, whole individual 2.118 grams #641

Description

Meteorite: NWA 7831 HED Achondrite Diogenite, whole individual 2.118 grams #641
On Offer:
2.118
grams whole individual of NWA 7831
Type:
HED Achondrite Diogenite
SEE OFFICIAL METEORITICAL SOCIETY ENTRY BELOW:
Northwest Africa 7831
Basic information
Name:
Northwest Africa 7831
This is an OFFICIAL meteorite name.
Abbreviation:
NWA 7831
Observed fall:
No
Year found:
2013
Country:
Western Sahara
Mass:
20 kg
Classification
history:
Meteoritical Bulletin:  MB 103
(2014)
Diogenite
Recommended:
Diogenite
This is 1 of 505 approved meteorites classified as Diogenite.
Search for other: Chondrites, Diogenites and HED
achondrites
Comments:
Approved 6 Sep 2014
Writeup
Writeup from MB 102:
Northwest Africa 7831
(NWA 7831)        27.307°N, 12.083°W
Saguia el Hamra, Western Sahara
Found: 2013 Mar
Classification: HED achondrite (Diogenite)
History
: Found buried in the ground near Chouichiyat on March 3, 2013, and excavated by a team of local people.
Physical characteristics
: A single large mass (at least 20 kg) composed of yellow-green crystalline material with pale orange weathering products along numerous fractures. Much of the material disintegrated into fragments upon excavation.
Petrography
: (A. Irving and S. Kuehner,
UWS
) The specimen is composed almost entirely of translucent, yellow-green orthopyroxene with very sparse, tiny included grains of Ni-free metal, troilite, chromite, anorthite, silica polymorph and clinopyroxene. Secondary pale orange, clay-like deposits from terrestrial weathering are present along thin fractures.
Geochemistry
: Orthopyroxene (Fs
28.1-28.3
Wo
3.0-3.3
; FeO/MnO = 29-31), clinopyroxene (Fs
10.9
Wo
43.1
, FeO/MnO = 26). Oxygen isotopes (K. Ziegler,
UNM
): analyses of acid-washed orthopyroxene by laser fluorination gave, respectively, δ
17
O = 1.677, 1.793, 1.810; δ
18
O = 3.680, 3.879, 3.875; Δ
17
O = -0.266, -0.255, -0.236 per mil.
Specimens
: 44.5 g of material is on deposit at
UWB
. The remainder is held by several anonymous collectors.
Data from:
MB 103
Table 0
Line 0:
State/Prov/County:
Saguia el Hamra
Date:
2013 Mar
Latitude:
27.307°N
Longitude:
12.083°W
Mass (g):
>20000
Pieces:
1
Class:
Diogenite
Shock stage:
low
Weathering grade:
moderate
Ferrosilite (mol%):
see text
Classifier:
A. Irving and S. Kuehner, UWS
Type spec mass (g):
45.4
Type spec location:
UWB
Main mass:
Anonymous
Comments:
Submitted by A. Irving
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