Northwest Africa 4423
Morocco
Find: May 2006
Carbonaceous chondrite (CK3)

History: A stone, said to have been found near Hammada du Guir, Morocco, was purchased by P. Thomas in May 2006.

Physical characteristics: One stone, weighing 91.94 g, entirely covered with a very black fusion crust.

Petrography: (M. Bourot-Denise, MNHN) Chondrules and CAIs are clearly visible to the naked eye and are mm-sized; CAIs are particularly abundant. Magnetite, the most abundant opaque mineral, makes large nodules around chondrules or, in association with sulfides (mostly pyrrhotite), in the matrix; it is also found as smaller grains rimming chondrules, AOAs and CAIs, and in chondrule rims; very small flecks of magnetite are located in a few areas of finer matrix. In BSE images, the chondrite appears not to be completely equilibrated, with zoned olivines and low-Ca pyroxenes in POP chondrules. Outside chondrules, high-Ca pyroxene is augite and diopside. The studied polished section features a large CAI, 3000 µm in size, rimmed with small magnetites.

Geochemistry: Olivine (mean Fa = 16.4 ± 12.7, range 0.31- 32.7), low-Ca pyroxene (Fs = 7.9 ± 8.6, range 1.1-24.1; magnetite (Cr2O3 = 2.35, MgO = 0.84 [both in wt%]), plagioclase (An22.6-77.6). Magnetic susceptibility: (J. Gattacceca, CEREGE) = log χ = 4.7 10-9 m3/kg.

Classification: Carbonaceous chondrite (CK3; estimated subtype 3.8); minimal shock and moderate weathering.