Northwest Africa 2180

Northwest Africa, purchased Erfoud

Find: 2002

Carbonaceous chondrite (CV3)

History: A number of stones were bought in Erfoud, Morocco, by an anonymous buyer, who owns the main mass.

Physical characteristics: The total mass is 369.3 g. The main mass weighs 51.4 g and has very small portions of a dark brown fusion crust. A cut surface on the type specimen shows rather large chondrules and some small white spots.

Petrography: (V. Moggi Cecchi and G. Pratesi, MSP) In thin section, several chondrules of various kinds (BO, PO, POP) accounting for ~50 vol% and ranging from 500 to 600 µm in size are visible, set in a fine intergrowth within phyllosilicates. The chondrule margins are clear and defined. Chondrules contain variable amounts of clear glass. The matrix is represented by olivine and orthopyroxene, with rare clinopyroxenes. Fe,Ni metal and troilite are uncommon (<5 vol%). CAIs and rare apatite grains are also observed.

Mineral compositions and geochemistry: Chondrule olivine (Fo_91–99), matrix olivine (Fo_31–56), orthopyroxene (En_98.1Wo_1.1), clinopyroxene (Fs_0.5–0.9En_59.4–93.2Wo_6.3–39.6). Chondrule glass is anorthitic (An₉₀). Oxygen isotopes: (I. Franchi and R. Greenwood, OU) δ¹⁷O = −0.718, δ¹⁸O = 4.032, Δ¹⁷O = −2.815 (all ‰).

Classification: Carbonaceous chondrite (CV3); S1, minor weathering

Type specimen: A total of 20.7 g and one thin section are on deposit at MSP. An anonymous buyer holds the main mass.