Newly Discovered Mesosiderite containing Achondrite Fragments : the Mount Padbury Meteorite

Abstract

As the result of an unusual find by the joint managers of Mount Padbury sheep station, near Meekatharra, Western Australia (latitude 25° 40′ S.; longitude 118° 06′ E.), a peculiar occurrence of ferruginous coated boulders has been investigated and recognized as mesosiderite material of meteoritic origin. This new find, resulting in the recovery of more than 600 lb. of material including a single 195-lb. mass, ranks only second to the recovery after an observed fall at Estherville, Iowa, in 1879, of 340 kg (750 lb.) of mesosiderite material (ref. 1, p. 119). Not more than a score of these stony irons are known (ref. 2, p. 122); they are much rarer than pallasites, and some of them are diminutive fragments or very weathered, and so are of little use for the purpose of precise petro-graphical investigations. This new find from Mount Padbury would be important on account of the amount of the material in itself, and the fact that, though many fragments are weathered to iron-shale, some are completely fresh and covered by only a thin iron oxide veneer. But it assumes an even greater significance with the recognition of enclaves of achondrite material up to an inch or so across and free, or nearly free, from nickel–iron, which are included within the mesosiderite matrix alongside large single crystals of olivine and lumps of solid nickel–iron. Such material must provide an opportunity to find out more about this somewhat variable group of stony-irons and even learn more concerning the wider problem of meteorite genesis.