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PLNClassification: Achondrite (ungrouped, anorthite-rich)
Place/Time: 2022 in Ghadamis, Libya
Mass: 440g
History: Found in northwestern Libya and purchased by Aziz Habibi in August 2022 from a dealer in Agadir, Morocco.
Physical characteristics: The exterior of this distinctive specimen (440 g) is partially coated by thin translucent fusion crust varying in color from beige to almost black. The fresh interior is overall almost pure white in color and is composed predominantly of white prismatic grains with subordinate yellow-green equant grains.
Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Relatively coarse grained aggregate with some finer granular regions (mean grainsize ~0.7 mm). Composed predominantly of anorthite (76 vol.%) and subordinate orthopyroxene (24 vol.%) together with accessory low-Ti chromite and troilite. Because of the simple and homogeneous mineralogy of this meteorite, it was possible to compute an accurate mineral mode from bulk rock XRF results and mineral compositions determined by EMP analysis.
Geochemistry: Anorthite (An95.4-95.6Or0.1-0.2, N = 3), orthopyroxene (Fs24.5-25.2Wo2.3-2.6, FeO/MnO = 26-28, N = 4). Oxygen isotopes (C. Sonzogni and J. Gattacceca, CEREGE): analysis by laser fluorination of a 1.5 mg aliquot from acid-washed powder produced by powdering a 85 mg bulk sample gave δ17O 1.774, δ18O 3.821, Δ17O -0.236 per mil (for a TFL slope of 0.526).
Classification: Achondrite (ungrouped, anorthite-rich with diogenitic affinities). Despite the apparent mineralogical and oxygen isotopic affinities with diogenites, it is recommended that such a highly feldspathic achondrite should not be called a diogenite (even a noritic diogenite). The amount of plagioclase is insufficient (<90 vol.%) for the term anorthositic to be applied.
NOTE: Material is fresh but fragile so slices was not polished, its impossible to do. Thickness of slices is only 2mm, please handle them gently.
