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The Los Angeles Meteorite

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Meteorite: Los Angeles
Location: Los Angeles County, California
Found: October 30, 1999
Type: Shergottite (SNC)

The Los Angeles Meteorite

Los Angeles 001
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A Mars meteorite stone (shergottite) weighing 452.6 grams. A 1 cm square cube is shown for scale.
Los Angeles 002
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A Mars meteorite stone (shergottite) weighing 245.4 grams. A 1 cm square cube is shown for scale.

New Mars Meteorite Found In California

By Ron Baalke
January 30, 2000

I'm very pleased to report on a new Mars meteorite find by a good friend and fellow meteorite collector, Bob Verish. The meteorite was found somewhere in the Mojave Desert in California, and consists of two stones of 452.6 & 245.4 grams. The two rocks have been classified as Mars meteorites, specifically basaltic shergottites, by analysis done at UCLA. The new meteorite's official name is the Los Angeles meteorite.


Los Angeles 001
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Side view of LA 001.

Los Angeles 001
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Closeup of the fusion crust on Los Angeles 001. LA 001 has a glossy fusion crust which is typical for basaltic meteorites.

Background

While on a rock collecting trip somewhere in the Mojave Desert in California, Bob Verish picked up a couple of rocks that had caught his eye. The rocks were basaltic with dark exteriors on top, and were interesting enough to his discerning eye to be included in his rock collection.

About 20 years would pass before Bob would look closely at the rocks again.

The rocks were stored in boxes in Bob's backyard along with a large portion of his rock collection. On October 30, 1999, while clearing out his rock collection for rat nests and rodent droppings, Bob came across the rocks again. Since Bob had begun collecting meteorites about 5 years ago, he now knew what meteorites looked like. He immediately noted the dark fusion crust on the rocks and suspected the two rocks to be meteorites. Bob cut off small samples of each rock (total weight of about 30 grams) which he would then take to Alan Rubin at UCLA for analysis.

New Mars Meteorite?

On December 17, 1999, UCLA confirmed the two rocks were meteorites. They also noted that upon viewing a thin section of the rocks, they bore a remarkable similarity with the QUE 94201 meteorite, a Mars meteorite found in the Antarctic in 1994. They suspected the rocks to also be Mars meteorites, but would require additional lab analysis for confirmation.

Shortly aftwards, Bob called me to say that he had more "rocks" for me to examine. Bob has brought many rocks to me over the years, rocks that people had lent to him thinking that they were potential meteorite candidates. Upon our closer examination, most of these rocks turned out be "meteorwrongs". But this time, while I was examining these "rocks", he casually informed me that I was holding a rock from Mars!

I took several photographs of the meteorites which are shown here on this web page. UCLA were busy analyzing the rocks though the Christmas break and wanted to submit papers on the meteorites for the upcoming Lunar And Planetary Science Conference (LPSC) being held in Houston in mid-March. The abstract deadline for the conference was January 12, 2000. UCLA was working hard to have confirmation of the rocks done by then, and had enlisted the help of Arizona State University.

Mars Meteorite Confirmed

By January 12, UCLA had confirmed the rocks were indeed Mars meteorites and had submitted three abstracts for the LPSC [1][2][3]. Meanwhile, Bob had reported his meteorite find to the Meteoritical Society, and the Nonmenclature Committee of the Meteoritical Society approved the name of Los Angeles for the newly discovered Mars rocks. Bob had affectionately and unofficially nicknamed the two Mars rocks as "Miguel" and "Gabriel"

In the petrology analysis led by Alan Rubin [1], the Martian origin for the Los Angeles meteorite was indicated by the D/H ratio. Apatite grains from the meteorite contained D-enriched water that was isotopically indistinguishable from comparable minerals from other shergotites. The rocks were shocked, which was also consistent with Mars meteorites. In the geochemistry analysis led by James Greenwood [2], the Los Angeles meteorite showed characteristic Martian values for such ratios as Mn/Fe, Na/Al and Ga/Al. It was also noted that the Los Angeles in many respects was the most geochemically evolved sample yet discovered from Mars.

Per Bob Verish [4], the following paragraph is a proposed draft of what is will appear in the Meteoritical Bulletin 84: Final version, 2000, July, MAPS 35:

            Los Angeles (original find location unknown)
            Los Angeles County, California, USA
            Recognized 1999 October 30
            Martian basalt (shergottite)
            Two stones, weighing 452.6 g and 245.4 g respectively, were
            found by Bob Verish in his back yard 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, 4.9 vol% silica, 4.2 vol% fayalite, 2.4 vol%
            K-rich felsic glass, 3.5 vol% titanomagnetite, 2.7 vol% Ca
            phosphate (including whitlockite and chlorapatite), 0.7 vol%
            pyrrhotite, and 0.2 vol% ilmenite; 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. [Houston LPSC references
            to be added later]

More Mars Meteorites?

I personally believe there are many more unidentified Mars and lunar meteorite sitting in collections waiting to be discovered. However, finding a new Mars meteorite is not an easy feat as Mars meteorites are extremely rare. Assuming the two Mars meteorites found in the Sahara Desert are paired, and the two new Los Angeles rocks are also paired, then the number of Mars meteorites is at only 14 [Update: additional Mars meteorites have been found since this article was written, so the number of Mars meteorites is now over 120!]. Compare that with the over 30,000 meteorites found on Earth. The Los Angeles meteorite is only the second Mars meteorite found in the United States. The other US find was the Lafayette meteorite found in Indiana. Like the Los Angeles meteorite, the Lafayette meteorite sat in a collection for a number of years before it was recognized as a meteorite. In Lafayette's case, it was discovered in the geological collection at Purdue University, and identified as a meteorite in 1931. There is a lot of work involved in identifying meteorites. Since 99% of the rocks brought in by the public turn out not to be meteorites, weeding through all of these "meteorwrongs" takes a lot of time and effort. But as the Los Angeles meteorite shows, the effort can sometimes be worth it.

2009 Update

In 2009, I attended a talk by Stephen Hawking at the Pasadena Convention Center. In the middle of his slideshow, a photo of Los Angeles meteorite appeared! It was one of the photos I had taken of the meteorite shortly after it was discovered.

References

[1] Rubin, Alan, et al, "The Pretology Of Los Angeles: A New Basaltic Shergottite Find", 31st Lunar And Planetary Science Conference.

[2] Warren, Paul, et. al, "Geochemistry Of Los Angeles, A Ferroan, La- and Th-Rich Basalt From Mars", 31st Lunar And Planetary Science Conference.

[3] Greenwood, James, et. al, "Late-Stage Crystallization Features Of Los Angeles, A New Balsatic Shergottite", 31st Lunar And Planetary Science Conference.

[4] Verish, Robert, The Los Angeles Meteorite Home Page.

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Please direct questions and comments about this home page to
Ron Baalke
Jet Propulsion Lab

ron@jpl.nasa.gov

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