Mason Gully                 [coordinates temporarily withheld]

Western Australia, Australia

Fell: 13 April 2010 at 10h36m10s UTC

Classification: Ordinary chondrite (H5)

History: A bright fireball was recorded over southwestern Australia by observatories of the Desert Fireball Network. A fall position was pin-pointed by triangulation (Pavel Spurny, CzAS), and a search was mounted (Martin Towner, ICL). A stone was recovered 3rd November 2010 within 150 m of the predicted fall site.

Physical characteristics: (Gretchen Benedix, NHM; Philip Bland, Kathryn Dyl, Martin Towner, ICL). An ~3 cm, 50% fusion crusted, 24.54 g stone was recovered.  Individual pyroxene, olivine, and feldspar crystals are visible on the broken surface, with no evidence of alteration of silicates. Some rust patches visible around metal grains on original broken surfaces. Although the meteorite appears to have high porosity (based on observations of sawn surfaces), metal in the interior shows no sign of alteration. Fusion crust is black and fresh.

Petrography: (Gretchen Benedix, NHM). The meteorite has a typical petrologic type 5 texture, with discernible, but not distinct chondrules. Chondrule types include BO and RP. Minerals are heterogeneously distributed. Modal mineralogy (in vol%) is: olivine 33; orthopyroxene 38; clinopyroxene 5; plagioclase 8; metal 11; sulfide 5; minor components around 1.

Geochemistry: (Gretchen Benedix, NHM; Richard Greenwood, Ian Franchi, Jenny Gibson, OU). Mineral compositions as determined by EMP: olivine, Fa_19.2±0.6; low-Ca pyroxene, Fs_16.±0.4Wo_1.4±0.3; chromite (Fe/Fe+Mg = 0.84; Cr/Cr+Al = 0.86). Oxygen isotopes: δ¹⁷O = 3.04‰; δ¹⁸O = 4.42‰; Δ¹⁷O = 0.74‰.

Classification: Ordinary chondrite (H5), S1, minimal weathering.

Specimens: The stone and one thin section are on deposit at WAM.