Acfer 366                                      26°36′56′′N, 03°56′14′′E

Acfer region, Libya

Find: November 2002

Carbonaceous chondrite (CH3)

History: A single stone weighing 1456 g was found in the Acfer region of Libya by Filiberto Ercolani (deceased 2004).

Petrography: (V. Moggi-Cecchi, A. Salvadori, and G. Pratesi, MSP) The outer surface displays a small portion of fusion crust. The stone is composed of 60 vol% lithic and crystal fragments, 20 vol% chondrules, and 30 vol% nonsilicate phases. Chondrules range from 30–300 µm with a mean apparent diameter of 90 µm. Chondrule textural types: cryptocrystalline (C) = 58%, granular olivine (GO) + granular olivine-pyroxene (GOP) = 22%, porphyritic olivine (PO) = 17%, and barred olivine (BO) = 3% (all vol%). Most of the larger chondrules are GO/GOP. Nonsilicate phases are mainly Fe,Ni metal (predominantly kamacite) and minor sulfides. The metal and sulfide grains range from 10–100 µm, are rounded to irregular in texture, and are homogeneously distributed through the meteorite, within and outside of chondrules.

Geochemistry: EPMA of chondrule olivine indicate a fairly homogeneous composition (Fo_97–100; mean Fo₉₇) although olivine in fragments has a more variable composition (Fo_80–99; mean Fo₉₅). Low-Ca pyroxene in chondrules and fragments is relatively homogenous (En_93–100Wo_1–5). High-Ca pyroxene is rare, occurring only in PO chondrules (Fs23.8Wo31.9). Plagioclase is found in chondrules and as angular fragments, and ranges from An₈₀ to An₁₀₀. Kamacite has a high Ni content (5–9 wt%). Sulfides are typically troilite (Ni = 1–2 wt%) although some pyrrhotite grains with Ni = 11 wt% are observed. Oxygen isotope: (I. Franchi and R. Greenwood, OU) δ¹⁷O = 1.781, δ¹⁸O = 4.610, ∆¹⁷O = −0.616 (all ‰).

Classification: Carbonaceous chondrite (CH3); S1, moderate weathering.

Specimens: A total of 30 g type specimen, one thin section, and the main mass of 1410 g are on deposit at MSP (inventory number MSP 2273).