Meteorite “Testing”

Meteorite “Testing”

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, 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.

Stony Meteorites

Check your own data with “Chemical Composition of Meteorites

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.

October, 2020: I have received results of analyses of 575 samples from Actlabs and 137 samples from other labs. Only 5 of the rocks have been meteoritic: 2 ordinary chondrites, 1 iron, 1 pallasite, and 1 apparent mixture (?) of meteoritic iron and terrestrial material. Two of the samples, I believe, were were from stones that someone had bought or inherited.

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.

X-ray “Guns”

People often send me data from a hand-held X-ray fluorescence (XRF) analyzer. Most of those data have been useless because the operators don’t know how to use the instrument for the specific purpose of identifying stony meteorites. They should be useful for iron meteorites, however.