Northwest Africa 2210

Morocco

Find: December 2004

Carbonaceous chondrite (CH3)

History: DGregory purchased a black, magnetic stone weighing 74 g in December 2004 from D. Bessey, who had obtained this material from a Moroccan dealer in Erfoud.

Petrography: (A. Irving and S. Kuehner, UWS) Relatively fine grained (10–89 µm) with glass spheres (En₉₉Fo₉₉) and chondrules (size range 10–80 µm), together with broken fragments of the same, in a sparse matrix.

Geochemistry: Abundant metal (15–20% by volume) which is mainly kamacite (5–10 wt% Ni), but in places taenite (Ni = ~20 wt%). Most of the chondrules contain very magnesian olivine (Fa₁) and/or orthopyroxene (Fs₁) in a mesostasis of glass, but some chondrules and fragments have more ferroan silicates (up to Fa50 and Fs50). Some cryptocrystalline chondrule fragments are composed of very fine intergrowths of low-Ca and high-Ca pyroxene and glass spheres have compositions intermediate between forsterite and enstatite. Other phases identified include Cr-Al-rich diopside, troilite, feldspathic glass, and rare, Al-rich chromite. No CAIs were observed. Oxygen isotopes: (D. Rumble, CIW) Analyses of two whole rock fragments by laser fluorination gave, respectively, δ¹⁸O = 3.95, 4.11; δ¹⁷O = 1.07, 1.05; ∆¹⁷O = −1.02, −1.12 (all ‰).

Classification: Carbonaceous chondrite (CH3).

Specimens: A 14.8 g type specimen and one polished thin section are on deposit at UWS. DGregory holds the main mass.