Mount Padbury meteorite, Mount Padbury Station, Meekatharra Shire, Western Australia, Australiai

Regional Level Types
Mount Padbury meteorite	Meteorite Fall Location
Mount Padbury Station	Mountain
Meekatharra Shire	Shire
Western Australia	State
Australia	Country

Stony-iron, Mesosiderite-A1
Find, 1964; 272 kg, largest mass 43 kg

Consisting of both large pieces and small fragments, the Mount Padbury meteorite was found during the mustering of sheep. It was soon recognized as a quite unusual mesosiderite. Volumetrically, the meteorite is dominated by various texturally and compositionally diverse silicates. Orthopyroxenes and lesser amounts of plagioclase are most prominent — both as individual crystals and as components of the fine grained matrix. Unusual olivine crystals enclosed by pyroxene-chromite rich coronas are also readily noted. Masswise, Fe-Ni metal (Ni~6%) accounts for slightly more than half of the meteorite mass (53 wt%). Much of the Fe-Ni metal is found as scattered, ganglion-like nodules which appear to have invaded the silicate regions. Significant amounts of troilite (~7 wt%) are also present. In addition to the usual metal and brecciated silicates, however, an unusual number of quite striking inclusions are found — most notable are the anorthositic, dunite, plagioclase-pyroxene ('eucritic'), and pyroxenite ('diogenite') inclusions. These inclusions are characterized by their mineralogy and, often, similarities to HED meteorite groups. Weathering is significant in places, but remarkably fresh regions can be found. Over the past few decades, these features and correlations — noted early by McCall (1966) — have been examined and amplified in great detail. And, of course, observations of additional silicates, opaques, and other phases have been reported.

Ar-Ar dating suggests that Mount Padbury's original parent body (OPB) — or, perhaps, an important fragment of the OPB — was involved in one or more important collisions between 3.5 and 4.0 billion years ago. Similar chronologies have also been reported for other mesosiderites. In the past decade, close and suggestive similarities in oxygen isotope ratios of mesosiderites with the (mostly) Vesta-derived HED meteorites have been confirmed. On the other hand, these same high resolution studies have also clearly separated the mesosiderites from the various pallasite groups and appear to rule out common OPB for the two major stony-iron groups.

Mt. Padbury is one of 7 meteorites classified as Mesosiderite-A1 (high plagioclase abundance; unmetamorphosed, fine-grained matrix). The main mass is at the Western Australian Museum in Perth. A 7 kg portion at the U.S. National Museum in Washington, DC is the most massive of several pieces that have been distributed elsewhere.

Other Regions, Features and Areas containing this locality

References