Meteorite**NWA 7831, Diogenite Achon.**21.535 gram slice; Asteroid 4 Vesta!!!!

Description

Hello up for sale is NWA 7831 classified as a Diogenite Achondrite. This gorgeous slice weighs 21.535 grams, has a perfect polish on one side and is translucent, high quality. It's composed of yellow-green crystalline material with pale orange weathering products along numerous fractures. 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. This meteorite comes with 2 COA cards, Streaming meteorites and Mark Lyon, and display case. Thanks for your interest and take care!
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
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 (Fs28.1-28.3Wo3.0-3.3; FeO/MnO = 29-31), clinopyroxene (Fs10.9Wo43.1, FeO/MnO = 26). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed orthopyroxene by laser fluorination gave, respectively, δ17O = 1.677, 1.793, 1.810; δ18O = 3.680, 3.879, 3.875; Δ17O = -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:
MB103
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
Diogenites
are an abundant type of achondrite, linked by geochemical traits such as oxygen isotopic ratios and certain elemental ratios, of which Fe/Mn is the most widely cited. The dominant mineral in diogenites is orthopyroxene. The diogenites are strongly linked with two other achondrite groups: eucrites and howardites; the three groups are collectively known as HED meteorites and may come from asteroid 4 Vesta. From the composition, scientists have concluded that the meteorite was formed at moderate depth under pressure in an asteroid. With 525 kilometers in diameter, the Vesta asteroid is the most obvious candidate. Because of the many collisions with other celestial bodies, pieces of rock and rubble have broken off and started to roam through space. By crossing the same path, these pieces of rock and debris hit the Earth and impacted as meteorites.