Watson 007        30°29’S, 131°41’E

South Australia, Australia

Found: 10 May 2009

Classification: Enstatite chondrite (EL3)

History: A single piece was found on the Nullarbor Plain by A. Langendam.

Physical characteristics: The 19.5 g specimen measures 3.2 x 2.7 x 1.2 cm. Some chondrules, as well as remnant fusion crust, are observable on the maroon-colored weathered surface.

Petrography: (Kim Lai N. Bell, Monash). This chondritic meteorite has sharply defined chondrules within a fine-grained, dark matrix. Mineralogy is dominated by orthopyroxene but also includes Fe-Ni metal, clinopyroxene, sulfides plus trace amounts of olivine. Chondrules (0.25-2 mm with an average of 0.7 mm) include RP and PP. Some glass present in the chondrules. Orthopyroxene grains have undulose extinction and irregular fracturing. Olivine is rare with the occasional small grain (<50 μm) occurring within PP chondrules. Fe-Ni metals (7%), plus sulfides (6%) occur as small irregular grains that have been heavily oxidized, with up to 97% being replaced. The chondrules are quite large with a high proportion exceeding 1 mm and the majority exceeding 0.5 mm, consistent with EL rather than EH chondrite classification and presence of manganoan daubréelite (Mg-free) also suggests EL rather than EH.

Geochemistry: EMPA (wt%) Olivine: SiO₂ = 41.77, TiO₂ = 0.00, Al₂O₃ = 0.03, FeO = 0.13, MnO = 0.02, MgO = 57.90, CaO = 0.02, Na₂O = 0.02, K₂O = 0.00, (Fa_0.22). Low-Ca pyroxene: SiO₂ = 58.82, TiO₂ = 0.01, Al₂O₃ = 0.19, FeO = 0.37, MnO = 0.01, MgO = 340.69, CaO = 0.28, Na₂O = 0.01, K₂O = 0.00 (En_99.92±0.21, n = 14). Troilite: Cr = 0.45, Ti = 0.48, Ni = 0.20. Daubréelite: Cr = 31.61, Ti = 0.13, Mn = 1.89, Ni = 0.07.

Classification: Enstatite chondrite (EL3, S2, W4).

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