Watson 015        30°34’22.10"S, 131°44’48.10"E

South Australia, Australia

Purchased: 2013 Apr 09

Classification: Ordinary chondrite (H4)

History: Large fragments found by A Langendam

Physical characteristics: A large 9 cm block with partial fusion crust, and a second small fragments with 65% fusion crust, both weathered brown.

Petrography: (J. Savage) Porphyritic chondrules range in size from 0.5 mm to an anomalous 4 mm, with an average size of 1.5 mm. Porphyritic chondrules smaller than 0.5 mm are indistinguishable from the matrix where as those in the size range mentioned above are easily identified. Non-porphyritic chondrules are all of similar size (~1.5 mm) and their boundaries are easily differentiated from the matrix. Some chondrule boundaries show intergrowths of matrix/chondrule composition. Metal and metal-oxides are pervasive and constitute 30% of the matrix. Recrystallized glass makes up 10% of the matrix and the remaining 60% is made up from re-equilibrated chondrites of olivine-pyroxene composition. The mineralogy of the meteorite includes olivine, pyroxene, Fe-Ni metal and troilite. The chondrule types present are PP, POP, BO, C, GOP and PO. Most olivine and pyroxene grains have sharp extinction, with some finer grains beginning to develop undulose extinction. 98% of Fe-Ni metal has been oxidized with sulphides showing 60% weathering. Where troilite grains are still visible, weathering is localized on the grain rims.

Geochemistry: (J. Savage, Monash) Microprobe analyses show that olivine and pyroxene compositions are uniform: olivine Fa_18.7-19.6, mean Fa_19.2±0.3, n=5; Low-Ca pyroxene Fs_17.1-17.5, mean Fs_17.2±0.2, n=5.

Classification: Ordinary chondrite (H4, S2, W4)

Specimens: All specimens and one thin section held by A. Tomkins.