Meteorite “Testing”

Stony Meteorites

I’m retired and no longer have a laboratory. I do not analyze or “test” rocks to determine whether or not they are meteorites.

There are several different ways to test if a rock is a meteorite. As a geochemist, I suggest whole-rock analysis of chemical composition. For that, you need to send a sample to a commercial rock-testing laboratory. At a minimum I need data for Si, Al, Fe, Mn, Mg, Ca, Na, K, Cr, and preferably Ni and Co to determine if the rock is a meteorite. With data for those elements, I can say “yes” or “no” with considerable confidence 99% of the time. Data for As, Cu, Zn, and the rare-earth elements would be useful, too.

For many years I have recommended Actlabs. Ask for analysis code Meteorite(ICP/ICPMS). I have no financial interest in Actlabs, I just know they do a good job. Before contacting them, however, contact me first for some advice. Actlabs requests a 5-gram sample (a US nickel weighs 5 grams). However, they can do the analysis on as little as 1 gram if you request “no LOI” (loss on ignition, i.e., % weight loss when the sample is heated to a high temperature). LOI is sometimes useful, but never critical, for determining whether or not a rock is a meteorite. Send me a copy of the report (the XLS file) that Actlabs sends you and I will tell you whether the rock composition is consistent with that of a meteorite. If I conclude that the composition of your rock is not consistent with any kind of meteorite, then I may not be able to tell you just what kind of rock it really is. Rock-type identification requires other kinds of tests.

Please, do not bother Actlabs with questions like “Is this a meteorite?” They just analyze; let me do the interpretation of the data

December, 2020: I have received results of analyses of 613 samples from Actlabs and more than 100 samples from other labs. Only 10 of the rocks were meteorites, all ordinary chondrites. Half of these were from northern Africa or the Middle East and a couple, I believe, were stones that someone had bought or inherited.

Check your own data with “Chemical Composition of Meteorites

Iron Meteorites

If you have a chunk of metal that you think might be an iron meteorite, you need to have it analyzed (at a minimum) for iron (Fe), nickel (Ni), chromium (Cr), and manganese (Mn). Unfortunately, I do not know a lab that does this cheaply. If somebody out there does, let me know.

Hand-held XRF Analyzers

I know a few meteorite collectors who use hand-held XRF “guns” to recognize meteorites. Most of the results that I have been sent from XRF guns, however, have not been useful to me for determining if the rock is a meteorite. There are at least three problems. Most of the instruments are designed or programed to do analysis of metals, not rocks, so, for example, there are no data for Si (silicon). Second, data for Na and Mg are critical and those elements cannot be determined by x-ray fluorescence in air. Third, it seems that most users don’t really know what they are doing when it comes to rocks. For, example, a fellow contacted me once saying “Big time reputable gold dealer tested it with his X ray gun.” The big time reputable gold dealer told him that his rock contained “at least 15% Bohrium,” an element does not occur in nature and the only isotope of which has an ~85 millisecond half-life.