Lahrauli meteorite, Basti District, Uttar Pradesh, Indiai

Regional Level Types
Lahrauli meteorite	Meteorite Fall Location
Basti District	District
Uttar Pradesh	State
India	Country

Classification: Ureilite (Ca-poor achondrite).

A single stone, 900 g.

Late in the morning of 24 March 1955 the Lahrauli meteorite fell in the village of Lahrauli, Basti district, Uttar Pradesh, India. Little else is known about this small stone. However, Lahrauli is a ureilite and is one of only 6 witnessed ureilite falls. The primary constituents of ureilites are familiar — olivine plus one or two pyroxenes (usually pigeonite). However, the olivine and pyroxene are oddly accompanied by various polymorphs of elemental carbon. The carbon itself is an enigmatic mix of graphite and small diamonds (plus, sometimes, chaoite and/or lonsdaleite). As in many meteorites, small amounts of metallic iron (kamacite) and iron sulfide (troilite) are invariably present. Other minor opaque minerals have been reported (vide infra). The ureilites are particularly intriguing because of seemingly contrary implications of their seemingly ordinary igneous silicate mineralogy, their diverse oxygen isotope signatures, and their very unusual nitrogen isotope compositions. The two varieties of diamond (particularly, the hexagonal lonsdaleite) and other microscopic textures suggest enormous pressures and quick cooling associated with strong impacts. However, other features suggest vapor condensation processes. Both the relative importance and the timing of these nebular and collisional processes do not appear to be settled matters at this time.

References

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