Los Angeles

Los Angeles County , California, USA

Recognized 1999 October 30

Martian basalt (shergottite)

Two stones, weighing 452.6 and 245.4 g, respectively, were found by Bob Verish in his backyard while he was cleaning out a box of rocks that was part of his rock collection.  The specimens may have been collected ~ 20 years ago in the Mojave Desert.  Classification and mineralogy (A. Rubin, P. Warren, and J. Greenwood, UCLA):  a basalt with a texture closely resembling that of the QUE 94201; plagioclase laths, 43.6 vol%, An₄₁Or₄ to An₅₈Or₁, have been shocked to maskelynite; Ca-pyroxene, 37.7 vol%, ranges from Fs₄₅Wo₁₃ to Fs₄₅Wo₃₇ to Fs₇₂Wo₂₄; other mineral modes (in vol%), silica = 4.9, fayalite = 4.2, K-rich felsic glass = 2.4, titanomagnetite = 3.5, Ca phosphate = 2.7 (including whitlockite and chlorapatite), pyrrhotite = 0.7, and ilmenite = 0.2; contains a higher proportion of plagioclase than Shergotty or Zagami, and has pyroxene that is moderately more ferroan than that in QUE 94201.  Specimens:  main masses with finder; 30 g, UCLA; 20 g, SI. Note, one may encounter references to the two masses as Los Angeles 001 and 002, or stone no. 1 and stone no. 2, respectively; these are unofficial designations.