Northwest Africa 4587

Algeria

Find: September 2006

Achondrite (ungrouped)

History: G. Hupé purchased the rock in September 2006 in Erfoud, Morocco.

Physical characteristics: The meteorite comprises a single, dense stone (530 g) without fusion crust. The main constituent (pyroxene) is a distinctive deep brown color and several large opaque grains are visible.

Petrography: (A. Irving and S. Kuehner, UWS) Granular texture with large pyroxene grains (pigeonite with numerous fine, parallel exsolution lamellae of clinopyroxene) and interstitial polycrystalline plagioclase (with rims of silica against pyroxene). Accessory minerals are skeletal ilmenite, merrillite, Ni-bearing pyrrhotite and rare kamacite. One large oikocryst of ilmenite + Ti-chromite contains numerous chadacrysts of plagioclase, and has narrow rims of fayalitic olivine adjacent to surrounding pyroxene.

Mineral compositions: Pyroxene consists of host pigeonite (Fs_63.4Wo_6.9 FeO/MnO = 67.6, TiO₂ = 0.49 wt%) and lamellae of clinopyroxene (Fs_35.4Wo_38.9, FeO/MnO = 69.4, TiO₂ = 0.90 wt%); plagioclase (An₈₅); olivine rim adjacent to ilmenite (Fa_81.9, FeO/MnO = 112).

Classification: Achondrite (ungrouped). This very fresh stone is essentially identical to NWA 011, NWA 2400 and NWA 2976, and evidently is paired with them.

Specimens: A total of 20 g of sample is on deposit at UWS. GHupé holds the main mass.