Northwest Africa 3214

Northwest Africa

Find: 2005

Carbonaceous chondrite (CV3)

History: M. Chinellato purchased a single stone in Erfoud, Morocco, in 2005.

Physical characteristics: The original stone weighed 435.2 g. A cut surface on the type specimen shows a very dark gray color with rather large chondrules and some small white spots and no fusion crust.

Petrography: (V. Moggi Cecchi and G. Pratesi, MSP) In thin section many chondrules of various kinds (BO, PO, POP) are visible, accounting for ~50 vol% and ranging in size from 550 to 1150 µm in apparent diameter (mean value 930 µm) and are set in a dark brown matrix. 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 are also present.

Mineral compositions and geochemistry: Olivine in the chondrules is Fo-rich (Fo_91–94, mean Fo₉₂). Olivine in the matrix is less Fo-rich (Fo_81–88, mean Fo₈₆). Orthopyroxene is enstatitic (En_98.36Fs_0.72Wo_0.92). An augitic pyroxene with variable composition is also present (Fs_{17.54–30.61}, En_{24.12–35.97}Wo_{47.12–48.49}). Oxygen isotope: (I. Franchi and R. Greenwood, OU) δ¹⁷O = -1.84; δ¹⁸O = 2.67; Δ¹⁷O = -3.23 (all ‰).

Classification: Carbonaceous chondrite (CV3); S1, minimal weathering.

Type specimen: A total of 20 g and one thin section are on deposit at MSP. MChin holds the main mass of 32.5 g.