Brachina meteorite

Brachina meteorite
Type	Primitive achondrite
Class	Asteroidal achondrite
Group	Brachinite
Composition	olivine, plagioclase, clinopyroxene, iron-sulfide, chromite, chlorapatite, pentlandite, meteoric iron, melt inclusions
Country	Australia
Region	South Australia
Coordinates	31.300000°S 138.383333°E / -31.300000; 138.383333
Observed fall	No
Found date	26 May 1974
TKW	202.85 grams (7.155 oz) (2 fragments)

The Brachina meteorite is the type specimen of the brachinites class of the asteroidal achondrites.

Naming and discovery

The meteorite is named after Brachina in South Australia. Two fragments (total 200 g) were found by B.M. Eves at 31.300000°S 138.383333°E / -31.300000; 138.383333 on 26 May 1974.^[1]

Description

The mineral composition of the Brachina meteorite is olivine (80%), plagioclase (10%), Clinopyroxene (5.5%), iron-sulfide (3%), chromite (0.5%), chlorapatite (0.5%) and pentlandite (0.3%) and traces of meteoric iron. Melt inclusions consist of glass with orthopyroxene and anorthoclase. The chemical and mineralogical composition is similar to the Chassigny meteorite, but the trace elements are fundamentally different.^[2]

Parent body

Melt inclusions indicate that there were melting processes active on the brachinite parent body.^[2]

Classification

The meteorite was classified as a chassignite in 1978,^[3] but in 1983 trace element analysis showed that the Brachina meteorite was fundamentally different from Chassigny. It was therefore proposed that the meteorite should be the type specimen of a new meteorite class, the brachinites.^[2] This classification has remained valid since then.^[1][4]

See also

• Glossary of meteoritics

References

1. "Brachina". Meteoritical Society. Retrieved 15 December 2012.
2. Nehru, C. E.; Prinz, M.; Delaney, J. S.; Dreibus, G.; Palme, H.; Spettel, B.; Wänke, H. (1 January 1983). "Brachina: A new type of meteorite, not a chassignite". Journal of Geophysical Research. 88 (S01): B237. Bibcode:1983JGR....88..237N. doi:10.1029/JB088iS01p0B237.
3. Graham, A. L. (1978). "Meteoritical Bulletin, No. 55". The Meteoritical Bulletin. 55: 331. Bibcode:1978Metic..13..327G.
4. Grady, Monica M. (2000). Catalogue of meteorites (5th ed. rev. and enl. ed.). Cambridge: Cambridge University Press. ISBN 9780521663038.