Dalgety Downs meteorite, Dalgety Downs Station, Upper Gascoyne Shire, Western Australia, Australiai

Regional Level Types
Dalgety Downs meteorite	Meteorite Fall Location
Dalgety Downs Station	Downs
Upper Gascoyne Shire	Shire
Western Australia	State
Australia	Country

Ordinary chondrite, (L4; S3; W5)
Found, 1941; 474 kg

A mass of 217.kg, broken into fragments, was found south of Dalgety Downs. Several additional masses, including another fragmented mass of 40.9 kg, were recovered in subsequent decades. Chondrules — porphyritic (PO, POP) plus barred olivine (BO) and radiating pyroxene (RP) — are readily observed. However, the chondrules are often poorly delineated and intergrown within a relatively coarse-grained matrix. Total iron (22.61 wt.%), olivine composition (Fa 25.2 mol%), and orthopyroxene composition (Fs 21.4 mol%) are characteristic of the L (low iron) ordinary chondrite group. Mineralogically the meteorite consists primarily of dominant olivine and orthopyroxene accompanied by troilite and Fe-Ni metal. Minor plagioclase and chromite are also present. Several opaques phases are present in even smaller or even trace amounts (Ramdohr,1973). Moderate shock indicators (level S3) include mosaicized olivine grains. Weathering of Fe-Ni metal and sulfides is quite apparent (level W5). Cosmogenic nuclides in Dalgety Downs suggest a complex exposure history with a putative recent breakup producing the eventually meteorite after a slightly larger meteoroid had itself been produced during another previous relatively recent collision.

Dalgety Downs is the most massive meteorite classified exactly as an L4 chondrite at The Meteoritical Bulletin Database. The L group of ordinary chondrites represents ~ 45% of the classified witnessed meteorite falls with the L4 petrologic type a small subset accounting for < 10% of the group.

Large masses of Dalgety Downs have been kept at the American Museum of Natural History in New York (125 kg), the Western Australia School of Mines in Kalgoorlie (42 kg), and at Arizona State University in Tempe (26 kg) [2000].

Other Regions, Features and Areas containing this locality

References