An Article In Meteorite-Times Magazine
by Robert Verish

El Mirage Dry Lake 001

When is a meteorite "too small" to be classified?


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This article is about a meteorite that was found in October of 2000 by Paul Harris, editor of this Meteorite-Times. More specifically, this is an image gallery that tells a story about how a "type specimen" was cut from Paul's meteorite find. By the way, if you are not familiar with the term, "Type Specimen", this is the name for the sample that is cut from meteorites and that is used in the subsequent identification, characterization, and eventual classification of that find. This sample is typically 20 grams in weight, but for meteorites under 100 grams, it is expected to be 20% or more of the total weight of that find.

The above image is an "in-situ" shot, by Paul Harris, while his find was still in-place on the surface of the El Mirage playa, a dry lake located in San Bernardino County, California (just across the border with Los Angeles County) and only 60 miles north of the city of Los Angeles.

The following images were taken by this author in 2001.

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"Click" on the above image of El Mirage Dry Lake 001 for a Close-Up view!!

The above image is an attempt to give some idea as to the small size of this 1.5g meteorite. For a sense of scale, the specimen was placed next to a U.S. one cent "penny", as well as, a centimeter ruler and a 1 cm cube.

The image below is the same setting, but depicting the opposite side of the meteorite. Note that the 1 cm cube has been also turned over and now displays the "B"-side (for Bottom-side). This denotes that this is the bottom-side of the meteorite; the side that was down and in contact with the ground when it was found by Paul.

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"Click" on the above image of El Mirage Dry Lake 001 for a Close-Up view!!

Most of the images in this gallery are of Paul's find before it was cut. The images were taken by me because it was my responsibility to do the cutting. Since this little (1.5g) stone would never look the same after being cut, I wanted to make sure there were plenty of pre-cut images beforehand. Although I had never cut a "type specimen" from a meteorite this small on my rock saw, I accepted this responsibility because I knew that a successful cut would represent a benchmark of sorts for other small meteorites. It would be an example that meteorites of this size are NOT "too small" to be classified. They, too, deserve to be given an approved name, and therefore, be included in any formal meteorite study.

But, to be a "successful cut" it would not only have to result in a single endcut that was of sufficient mass to qualify as a type specimen, but it would also have to result in a remaining mass that survived the cut in one piece, AND had a good-looking cut surface. So the object was to have 2 pieces: 1) a type specimen that was large enough, and 2) a meteorite with a cut surface that was aesthetically appealing.

The last image in this gallery shows the specimen after it was cut.

In the image below, the meteorite has been placed next to the head of a pin.

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"Click"on the above image of El Mirage Dry Lake 001 to ENLARGE!!

In the image below it is the same view as the image above, but the meteorite has been magnified in order to show that the fusion-crust has formed a "roll-over lip" on what is best termed as the "aft-end" of this somewhat-oriented stone. For scale the head of the pin is ~2mm.

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"Click" the above image of El Mirage Dry Lake 001 to ENLARGE!!

In the image below, the "front-side" of this somewhat-oriented meteorite has been magnified and placed next to the head of a pin.

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"Click" the above image of El Mirage Dry Lake 001 to ENLARGE!!

The image below, is the same view as the image above, but it was taken at a different angle.

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"Click" the above image of El Mirage Dry Lake 001 to ENLARGE!!

In the image below, the meteorite has been turned counter-clockwise 90 degrees, and placed next to the ~2mm wide head of a pin.

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"Click" the above image of El Mirage Dry Lake 001 to ENLARGE!!

Most of the places that do meteorite classification expect that the meteorites they classify will eventually appear in the Meteoritical Bulletin. In many cases they even expect the find to have a NomCom approved "provisional name/number" assigned before being accepted for classification. And in order to get a provisional name or number assigned, the NomCom will ask, at a minimum, for the following information:

Mass (weight of find)?
Find locality (coordinates)?
When found (date of find)?
And, if the finder is anonymous, can the person submitting the meteorite vouch for all of the required information?

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"Click" the above image of El Mirage Dry Lake 001 to ENLARGE!!

Text...

We submitted all the "known" information about this meteorite to the Nomenclature Committee of the Meteoritical Society, and they agreed to give it a "provisional name and number". Now that an approved name has been assigned to this find, we were now ready to submit the type specimen to UCLA for classification.

And below is the actual classification as determined by UCLA:

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This image depicts EMDL 001 at "ACTUAL SIZE"!!


Here is what we now know about Paul's meteorite find:
El Mirage Dry Lake 001
 
Find. Date of find - 2000 October 14 
 
Stone. Chondrite, Ordinary (H5, S3, W2, olivine Fa 18.6 +/-0.3)
 
Approx. recovered weight:  1.50 grams
 
One stone of 1.5g was found by Paul Harris of Redondo Beach, California.  
Mineralogy - H-chondrite (0.30 gram type specimen was submitted to Alan Rubin, UCLA).  
This flat, square button-shaped, yet slightly wedge-shaped, stone has a fresh 100% fusion-crust.  
The stone is uniformly spotted with orange "rust-blisters" on its brownish black exterior, and its interior is a fresh, light-brown color but the groundmass is mottled throughout with orange spots, as well.  
The exterior of this stone is NOT smooth to the touch, which is not typical of meteorites found on most drylakes.  
This is indicative of a short history of terrestrial residence where, even if this stone was exposed to wave action, 
the physical weathering was of a low energy. 
Generally speaking, the chondrules are uniform in size and distribution throughout the 
groundmass (with chondrules ~60%, and groundmass ~40%).  
The chondrules and groundmass are moderately equilibrated. 

 
Specimens:  0.30 grams (type specimen), UCLA, Los Angeles; 
main mass with finder (Paul Harris).
 

 

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And here is EMDL 001 AFTER THE CUT!

From the above image it appears that the cut was a success. The cut reveals even more about this find. And now Paul has a meteorite with an attractive cut surface that tells an interesting story.

What we now know about Paul's meteorite from this cut surface:

The above close-up image reveals an interior that has a uniformly mottled groundmass, exhibiting tarnished sulfide grains and metal grains that have partially oxidized, This oxide has locally stained the matrix with a rusty color producing the "mottled" appearance. There is a sharp demarcation between the fusion-crusted exterior and the lighter-colored interior. And the few, small chondrules that are visible are clearly equilibrated with the crystalline groundmass, which indicates this stony to be an equilibrated Ordinary Chondrite (OC).

 

The meteorite shown in this article was first published in the 2002 Meteoritical Bulletin.

If you have any information relating to the El Mirage Dry Lake meteorites, please contact me by email: Bolide*chaser

REFERENCES:

Google Web Search Results 1 - 3 of about 6 for El Mirage Dry Lake 001 . (0.09 seconds) 

Meteoritical Bulletin: Entry for El Mirage Dry Lake 001

El Mirage Dry Lake 001. Information about the name, Name: El Mirage Dry Lake 001 This is an OFFICIAL meteorite name. There is no official abbreviation for ...
tin.er.usgs.gov/meteor/metbull.php?code=7810 - 26k - Cached
[KML]

kml file

... <latitude>34.654330</latitude> <range>50000.0</range> </LookAt> <Placemark> <name>El Mirage Dry Lake 001</name> <description> H5; mass=1.5 g; ...
tin.er.usgs.gov/meteor/index.php?sea=El+Mirage+Dry&sfor=names&stype=starts&lrec=50000&map... - 8k - Cached

Meteorite Times Magazine Articles - Meteorites & Tektites ...

Some other people had found one of the dry lakes to be the perfect location for a golf ... Paul's - El Mirage Dry Lake 001 - H5 S3 W2 1.5gms - New Find ...
www.meteorite-times.com/Back_Links/2002/April/Meteorite_People.htm - 15k - Cached


My previous articles can be found *HERE*

For for more information, please contact me by email: Bolide*chaser