On Offer:  48.73g Ureilite (augite-bearing) full slice of NWA 11900 - Primitive Achondrite Meteorite.

Dimensions: 103.72 mm x 80 mm x 2.65 mm

Official name: NWA 11900

Classification: Ureilite (Augite-bearing) 

Description:  A 48.73 gram complete slice, polished on one side, of the augite-bearing Ureilite achondrite meteorite NWA 11900. This ureilite is one of the more rare augite-bearing ureilite classifications. Most ureilite meteorites have a primary composition of a mix of olivine and pigeonite. Pigeonite is a type of pyroxene with a lower Ca (Wo5-25) than augite (Wo24-40). This ureilite has a less common mix of olivine, and two types of pyroxene; pigeonite and augite. This is why it is considered an "augite-bearing" ureilite.

The ureilite meteorites are famous for having large equant olivine and pyroxene crystal grains, as well as a relatively large amount of graphite. Occasionally this graphite, which is made of the element carbon is put under such intense pressure (likely due to hypervelocity collisions of its parent asteroid with other asteroids) that microscopic faulted and twinned cubic diamonds are formed. These extraterrestrial diamonds are known as "lonsdaleite". 

The Ureilite meteorites are considered to be "primitive achondrites". This is in reference to their having some characteristics similar to the more evolved and differentiated achondrites, while also displaying some characteristics of less evolved recrystallized chondrites. In this way, they are "primitive". They are closer to achondrites than to chondrites, but they have not quite evolved from their chondritic precursors into fully fledged achondrites.

What you get: 48.73 gram slice of NWA 11900 augite-bearing Ureilite meteorite specimen as shown, membrane storage/display box, and signed Certificate of Authenticity.

I offer a 100% no questions asked 30 day return policy.  

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Northwest Africa 11900
Basic information	Name: Northwest Africa 11900      This is an OFFICIAL meteorite name. Abbreviation: NWA 11900  Observed fall: No Year found: 2017 Country: Western Sahara  Mass: 457 g
Classification   history:	Recommended: Ureilite    This is 1 of 475 approved meteorites classified as Ureilite.   [show all] Search for other: Achondrites, Ureilites
Comments:	Approved 2 Sep 2018
Writeup:	Writeup from MB 107:  Northwest Africa 11900 (NWA 11900) Western Sahara Purchased: 2017 Classification: Ureilite History: Purchased by Dustin Dickens from nomad near Dahkla in Western Sahara. Physical characteristics: Weathered exteri; saw cut reveals an interior mosaic of green and brown crystals. Petrography: (C. Agee, UNM) This meteorite consists of olivine, pigeonite, and augite. Ubiquitous fine-grained Fe-metal is present along grain boundaries. Elongate (100-200 μm) grains of graphite are scattered throughout. Geochemistry: (C. Agee, UNM) Olivine Fa22.2±0.1, Fe/Mn=49±1, Cr2O3=0.36±0.02 (wt%), n=7; pigeonite Fs18.6±0.3Wo4.2±0.1, Fe/Mn=29±1, n=4; augite Fs11.7±0.1Wo34.9±0.1, Fe/Mn=22±1, n=3. Classification: Augite-bearing ureilite Specimens: 20.7 g including a probe mount on deposit at UNM, Dustin Dickens holds the main mass.
Data from:   MB107   Table 0   Line 0:	Place of purchase: Western Sahara Date: P 2017 Mass (g): 457 Pieces: 1 Class: Ureilite Shock stage: low Weathering grade: moderate Fayalite (mol%): 22.2±0.1 Ferrosilite (mol%): 18.6±0.3, 11.7±0.1 Wollastonite (mol%): 4.2±0.1, 34.9±0.1 Classifier: C. Agee, UNM Type spec mass (g): 20.7 Type spec location: UNM Main mass: Dustin Dickens Comments: Field name DD-27; submitted by C. Agee, UNM