Watson 005        30°30’S, 131°42’E

South Australia, Australia

Found: 9 May 2009

Classification: Ordinary chondrite (H5)

History: A solitary piece found by A. Langendam on the stony surface of the Nullarbor Plain.

Physical characteristics: This meteorite is dark maroon in color, weighs 1.6 g and measures 1.7 cm on the longest axis. Small chondrules and metallic grains are best observed on a fresh surface.

Petrography: (Kim Lai N. Bell, Monash). Readily discernible chondrules lie in a heavily stained matrix, which makes it difficult to gauge the amount of recrystallization in the matrix. Chondrules are devoid of glass and range from 0.25-1 mm in size with an average of 0.3 mm. Textural types include RP, POP, BO and PO with some of the latter rimmed by olivine. Mineralogy consists of olivine, pyroxenes, feldspar, Fe-Ni metal and sulfides. Olivine and pyroxene grains have a straight to undulose extinction with planar fracturing evident in larger grains. Twinned plagioclase occurs as an accessory mineral and is generally <50 μm in size. Metal phases (5%) include kamacite and taenite, which can occur as small irregular shaped grains. Troilite (7%) also occurs in a similar fashion to the metallic phases. Both metal and sulfide minerals have been oxidized, with up to 28% of these minerals being replaced by oxides.

Geochemistry: EMPA (wt%) Olivine: SiO₂ = 38.81, TiO₂ = 0.02, Al₂O₃ = 0.01, FeO = 17.96, MnO = 0.45, MgO = 42.45, CaO = 0.03, Na₂O = 0.01, K₂O = 0.00, (Fa = 19.19 mol%, σ = 0.34, n = 8). Low-Ca pyroxene: SiO₂ = 55.62, TiO₂ = 0.06, Al₂O₃ = 0.14, FeO = 12.43, MnO = 0.46, MgO = 30.79, CaO =0.39, Na₂O = 0.02, K₂O = 0.00, (Fs = 18.43 mol%, σ = 2.27, n = 4). Feldspar: SiO₂ = 64.97, TiO₂ = 0.01, Al₂O₃ = 18.45, FeO = 1.20, MnO = 0.00, MgO = 0.00, CaO = 0.00, Na₂O = 0.71, K₂O = 16.38, (Or = 93.12 mol%).

Classification: Ordinary Chondrite (H5, S2, W2).

Specimens: Single sample and one thin section held by A. Tomkins at Monash.