SRI's

April, 2000

Lab Photo Homepage

Los Angeles 001

A New Martian Shergottite

Analysis and description by:

Russell Kempton, New England Meteoritical Services

Los Angeles 001, paired with Los Angeles 002, represents the 14th verified Martian meteorite. This new addition to our collection of rocks from Mars has been classified as a basaltic shergottite (the fifth one after Shergotty, Zagami, EETA79001, and QUE94201) and is the most geochemically evolved sample of the Martian surface found to date on Earth.

Los Angeles 001 is unusually coarse-grained indicating that it cooled from igneous temperatures (1200 C to 900 C) at a slower rate than other shergottites. This slower cooling resulted in a crystallization of the pyroxenes augite and pigeonite in lamellae easily visible to the unaided eye. In comparison, the augite in Zagami is almost an order of magnitude smaller than that observed in LA001.

Augite and pigeonite lamellae

Augite within pigeonite

Los Angeles 001 fusion crust and exterior

The glossy-black fusion crust on sections of LA001 is typical of eucrites and other Martian meteorites. It differs however in thickness. The crust on LA001 is thinner - around .2 mm. This could be due to spending less time in atmospheric transit, entry velocity, or angle of entry. The terrestrial age of LA001 is not known yet but the presence of this thin crust - shiny black and still intact argues for a short terrestrial age*.

Fusion crust visible on the outside surface

The actual location where LA001 was found is not known. However the analysis of terrestrial soil deposits bear a strong resemblance to similar deposits on meteorites found at the Gold Basin strewnfield, Mohave Co., Arizona.

For a better understanding of Fusion Crust

This slice of LA001 was sent to us by a NEMS customer who had purchased it elsewhere. The customer asked us to remove the "saw blade" cutting marks from the specimen and allowed us to extensively photograph it.

References:

Warren P.H. et al. "Geochemistry of Los Angeles, a Ferroan, La- and Th-Rich Basalt From Mars", 2000, LPSC31

Rubin A.E. et al. "Petrology of Los Angeles: A New Basaltic Shergottite Find", 2000, LPSC31