Northwest Africa 3157

Morocco or Algeria

Find: September 2004

Ordinary Chondrite (Type 3)

History: Purchased from a Moroccan dealer at the Denver Mineral Show by A. Hupé in September 2004.

Physical characteristics: A single 51.7 g light brown stone lacking fusion crust and with abundant, large chondrules.

Petrography: (A. Irving and S. Kuehner, UWS): Closely packed PO and POP chondrules (mean diameter 1.0 mm); some are ovoid. The matrix is a "lacework" of porous olivine and pyroxene with accessory kamacite, taenite and troilite. The content of metal (+ minor Fe hydroxide) is very low (mode determined by BSE imaging of a whole thin section is 1 vol.%).

Geochemistry: Olivine (Fa_0-60); orthopyroxene (Fs_0.5-30Wo_1.5) Oxygen Isotopes: (D. Rumble, CIW) Analyses of two acid-washed whole rock fragments by laser fluorination gave, respectively, δ¹⁸O = 5.30, 4.85; δ¹⁷O = 3.48, 3.29; Δ¹⁷O = 0.693, 0.742 (all ‰). Although these Δ¹⁷O values are within the range for H chondrites, this specimen is poorer in metal than typical H chondrites.

Classification: Ordinary chondrite (Type 3); S2, W1/2.

Specimens: A total of 10.6 g of sample and one polished thin section are on deposit at UWS. Hupé holds the main mass.