Northwest Africa 8679 (NWA 8679)

(Northwest Africa)

Purchased: 2014 Sep

Classification: Martian meteorite (Shergottite)

History: Purchased by Dr. David Gregory in September 2014 from a Moroccan dealer at the Denver Show.

Physical characteristics: (I. Nicklin and K. Tait, ROM) Ellipsoidal stone (285 g) partly covered by black fusion crust. Wire-saw cutting revealed the fresh, gray interior, which is relatively fine-grained with visible glassy maskelynite.

Petrography: (A. Irving and S. Kuehner, UWS) Intersertal texture. Composed predominantly of prismatic grains (up to 1.8 mm long) of clinopyroxene (exhibiting complex, patchy compositional zoning) and lath-shaped grains (up to 1.2 mm long) of maskelynite, with accessory ulvöspinel, ilmenite, pyrrhotite and rare merrillite.

Geochemistry: (S. Kuehner and A. Irving, UWS) Subcalcic augite (Fs_21.1-37.2Wo_31.6-33.9, FeO/MnO = 28-37, N = 8), pigeonite (Fs_29.9-59.7Wo_9.8-16.9, FeO/MnO = 32-38, N = 12), plagioclase (maskelynite) (An_47.9-54.1Or_1.5-1.3, N = 3). Oxygen isotopes (K. Ziegler, UNM): analyses of four acid-washed subsamples by laser fluorination gave, respectively, δ¹⁷O 2.742, 2.896, 2.845, 2.642; δ¹⁸O 4.680, 4.974, 4.934, 4.562; Δ¹⁷O 0.271, 0.270, 0.240, 0.233 (all values in per mil).

Classification: Martian (shergottite).

Specimens: 23 g plus one polished thin section, one polished thick section and a polished epoxy mount at ROM. The remainder is held by DGregory.