Northwest Africa 1665

Northwest Africa

Found 2002

Carbonaceous chondrite (CK3 anomalous)

A single stone of 1185 g covered by fusion crust was found in 2002 by an anonymous finder in the Occidental Saharan desert. Classification and mineralogy (A. Greshake and M. Kurz): it is a type 3 carbonaceous chondrite with chondrules, irregular shaped olivine-rich objects, and mineral fragments set into a fine-grained matrix of Fe-rich olivine, Ca-pyroxene, troilite, and FeNi-metal; chondrules have a mean diameter of 130 µm and porphyritic olivine and pyroxene chondrules clearly dominate over radiating or cryptocrystalline types; matrix abundance is about 50 vol%; olivine, Fa_25.7 (range Fa_0.7-37.6); pyroxene, Fs₁₂ (range Fs_2.5-48.3); oxygen isotopic compositions (R. Clayton and T. Mayeda, UChi): δ¹⁸O = -1.03‰, δ¹⁷O = -4.95‰ and (I. Franchi and R. C. Greenwood, OU): δ¹⁸O = -1.88‰, δ17O = -5.43‰, Δ¹⁷O = -4.45‰ are clear of the CO3 chondrite field and possibly located on an extension of the CK3 range; shock stage, S1; weathering grade, W2. Specimens: Main mass with anonymous finder; type specimen 22 g plus one polished thin section MNB.