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Buseck Center for Meteorite Studies


October’s Meteorite of the Month is Bilanga, an achondrite meteorite (meaning that it formed on a differentiated planetary body, and does not contain chondrules) that fell in Burkina Faso, October 27 of 1999.

According to the Meteoritical Bulletin (MB84):

After a widely witnessed shower, at least 25 kg of meteorites with fresh black fusion crust were collected, comprising many stones. Pieces are reported to have fallen in the villages of Bilanga-Yanga and Gomponsago.

Bilanga is a diogenite. Part of the HED (Howardites, Eucrites and Diogenites) group of achondrites, diogenites are believed to originate in the crust of Asteroid 4-Vesta. According to radioisotope dating, the HED achondrites crystallized between 4.43 and 4.55 billion years ago. Diogenites are plutonic igneous rocks that form deep in the crust and cool very slowly, resulting in large crystals. They are named for the ancient Greek philosopher Diogenes, who was the first to suggest that meteorites were not terrestrial rocks, and actually originated in space.

Photo © ASU/BCMS.

Bilanga stone showing interior and fusion crust.