Northwest Africa 13370 (NWA 13370)

Morocco

Purchased: 2020

Classification: HED achondrite (Howardite)

History: In February of 2020, Fabien Kuntz purchased two stones with a total weight of 311.8 g from a meteorite prospector in Guelmim, Morocco.

Physical characteristics: A sample from each stone was submitted for classification. Both stones have a dark-brown, wind-ablated exterior. Clasts are visible on the exterior. The cut face shows sample is a breccia with visible orthopyroxene clasts, lithic clasts up to 2 mm and flecks of Fe metal.

Petrography: Description and Classification (A. Love, App) Sample is composed of (vol %): angular to rounded lithic clasts of eucrite (70) and diogenite (30) and similar mineral fragments set within a comminuted matrix of these materials. Lithic clasts are: cumulate and equilibrated basaltic eucrite; diogenite (including a poikilitic diogenite) and a highly magnesian olivine-orthopyroxene lithology (Fa_5-Fs₁₃Wo_0.3); and several shock-melted clasts (melt breccia - total melt). Eucritic pyroxenes are exsolved. Additional minerals are olivine chromite, ilmenite, troilite, plagioclase, Fe metal grains and a silica polymorph.

Geochemistry: (A. Love, App) Diogenite: orthopyroxene (Fs_26.0±5.1Wo_1.7±1.1, Fe/Mn=32.2±4.1, n=12); Olivine, Fa_25.2±14.8 (Fa_5.6-47.7, Fe/Mn=40.6±6.8, n=9). Eucrite: low-Ca pyroxene (Fs_52.7±10.0Wo_3.2±1.2, Fe/Mn=29.4±1.4, n=5); pigeonite (Fs_42.7-49.7Wo_8.9-12.1, N=2); high-Ca pyroxene (27.5±7.0Wo_40.8±2.2, n=5); plagioclase (An_93.1±2.4Or_0.2±0.1, n=6).

Classification: HED achondrite (howardite). Based on texture, modal abundances, unequilibrated mineral compositions, Fe/Mn and Mg# of orthopyroxenes and olivines, this sample is a howardite with a shock stage corresponding to M-S2 and low weathering grade.

Specimens: Kuntz holds the main masses. Two slices weighing 29.78 g and a polished thin section are on Deposit at App.