Northwest Africa 1052

Morocco

Found 2001

Acapulcoite

A stone of 22 g was bought in Erfoud (Morocco) by Matteo Chinellato. Classification and mineralogy (G.Pratesi, V.Moggi-Cecchi, L. Mancini, MSP: petrography and EMPA; G. Sighinolfi and S. Lugli, UMo: EMPA): either thin section and type specimen sample look to be composed by a fine grained aggregate. In thin section it displays an granular texture with grains mainly represented by olivine, pyroxene, Fe,Ni alloy and troilite and ranging from 200 to 700 µm in dimensions. Olivine is homogeneous and has a typical forsteritic composition, (Fa_5.95); orthopyroxene Fs_7.60Wo_1.44. High Ca-pyroxene (Fs _3.63En _51.1Wo_45.3, Al = 1.44 mol %) and plagioclase (An_13.7Ab_79.9Or_6.4) are also common. Apart from silicates, major phases are metal and troilite. Accessory phases include Na- and Ca-Merrillite and magnesiochromite (Cr/(Cr+Al) = 0.91; Fe:Mn:Mg ratios = 0.58:0.09:0.33). This meteorite shows a recrystallization texture with abundant 120° triple junctions and  many interstices filled with metal. Based on texture (fine-grained), mineralogy and chemistry (Cr content of diopside varying from 1.18 to 1.43 wt. %) the meteorite is classified as an acapulcoite. Terrestrial weathering grade is rather low (W1); optical features (sharp extinction of olivine) indicate that the sample is very weakly or not shocked (S1). Specimens: main mass with buyer (Matteo Chinellato); type specimen (4.7 g) and thin section, MSP.