Sahara 99555 meteorite, Sahara Desert, North Africai

Regional Level Types
Sahara 99555 meteorite	Meteorite Fall Location
Sahara Desert	Desert
North Africa	- not defined -

Sahara 99555 (1999 find), 2.71 kg
Angrite, quenched
2nd most massive Angrite

The Sahara 99555 meteorite, recovered somewhere south of the Mediterranean Sea and north of the Equator, is an igneous rock rich in somewhat variable Olivine (~40%), Anorthite (~33%), Fassaite (~25%) and several minor constituents. Skeletal olivine and plagioclase crystals, among other features, suggest that it is a product of a rapidly cooling magma. Bulk Chemical considerations and specific mineralogical features (Kirschtenite, Ti-rich magnetite, etc.) mark Sahara 99555 as an Angrite, a relatively rare achondrite class with only 22 known members representing no more than 15 separate falls. Fortuitously enough, Sahara 99555 and D’Orbigny, the two largest angrites, appear to be compositionally identical with differences between the two being less than the inherent variability with the individual meteorites. Sahara 99555 is also remarkably free of most normal weathering products expected for a meteorite recovered without being observed to fall.

While some new mineralogical phases and features have been subsequently discovered, Mittlefehldt et al., (2002) have presented clear and detailed considerations which indicate the likelihood of a rather large original Angrite parent body (APB) — perhaps larger even than Vesta, the putative source of most Howardite-Eucrite-Diogenite (HED) meteorites. Recent studies have derived a ~4.563 billion year crystallization age for Sahara 99555 and a few of the Angrites. Others appear to be about 5 million years younger. One suggested explanation for these age differences is that Sahara 99555 and the other older Angrites crystallized closer to the surface than the other, more plutonic angrites which were insulated well beneath the surface of the APB.

Other Regions, Features and Areas containing this locality

References