Northwest Africa 7324 (NWA 7324)

(Northwest Africa)

Purchased: 2012

Classification: EH-melt rock

History: Purchased by Stefan Ralew in April and November 2012 from a dealer in Erfoud, Morocco.

Physical characteristics: A group of dark brown, dense stones comprising two larger pieces (one 3250 g) and many small fragments (total 4490 g). Fresh interiors are black with abundant metal and sulfide visible, and the specimens emit a very strong sulfurous smell upon cutting.

Petrography: (A. Irving and S. Kuehner, UWS) Entire specimen consists of a fine grained aggregates of highly magnesian silicates and abundant metal and sulfides with no interstitial glass. Minerals are euhedral enstatite, some forsterite, ragged grains of Si-bearing metal, rare euhedral graphite laths, Cr-bearing troilite, niningerite and rare oldhamite. Portions of the matrix consist of silica-rich glass (K-bearing) containing tiny crystals of a very Si-rich mineral (silica or possibly sinoite). A few relict chondrules were observed.

Geochemistry: Enstatite (Fs_0.4-0.7Wo_0.3-0.9, N = 3), forsterite (Fa_0.5, N = 1), metal (Si = 2.5 wt.%, Ni = 6.6 wt.%).

Classification: EH-melt rock.

Specimens: A total of 20.6 g of type material and one polished thin section are on deposit at UWB. The remaining material is held by Ralew.