Northwest Africa 13900 (NWA 13900)

(Northwest Africa)

Purchased: 2019

Classification: HED achondrite (Eucrite, monomict)

History: In May 2019 at the mineral show in Chenzhou Ziyao Wang discovered, on the bottom of a box with ordinary chondrites from northwest Africa, some small strange stones and donated them to Rainer Bartoschewitz. Some of these stones were meteoritic and others of terrestrial origin.

Physical characteristics: 31 g broken individual with about 60% black lustery fusion crust. The broken face shows orange-gray adhering soil.

Petrography: (R. Bartoschewitz, Bart) silicate fragments (pyroxene, feldspar, chromite and rare troilite) up to 0.7 mm and few gabbroic clasts up to 1 mm set in a fine grained matrix (<50 µm).

Geochemistry: (R. Bartoschewitz, Bart, P. Appel and B. Mader, Kiel) poor Ca pyroxene Fs_41-44Wo_2-5, FeO/MnO=30 (n=12); pigeonite En₄₉Fs₃₅Wo₁₆ (n=1); augite En_39-42Fs_17-19Wo_44-40 (n=2); feldspar An_93-96Or<1 (n=62); chromite CRAL=80-84, FFM=94-96 (n=17); troilite. Magnetic susceptibility (R. Bartoschewitz, Bart) log χ (× 10^-9 m³/kg) = 2.45

Classification: Eucrite, cumulate

Specimens: 6.2 g on deposit at IfP, main mass with Bart.