Meteorite Testing

Stony Meteorites

If you are particularly certain that your rock is a meteorite and you really want to convince me (or any other scientist), then I urge you to obtain a chemical analysis at a commercial rock-testing laboratory. I recommend Actlabs. Ask for analysis code Meteorite(ICP/ICPMS). I have no financial interest in Actlabs, I just know they do a good job. First, however, send me some photos of the rock so I get a chance to say, “If that rock were mine, I wouldn’t spend the money to have it analyzed.”

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 that Actlabs sends you (XLS file) and I will tell you whether the rock composition is consistent with that of a meteorite. A chemical analysis is sufficient for me to be able to say “yes, it is” or “no, it’s not” 99 times out of 100. If I conclude that the composition of your rock is not consistent with any kind of meteorite, then I will probably not be able to tell you just what kind of rock it really is. Rock-type identification requires other kinds of tests.

Check your own data with “Chemical Composition of Meteorites

If you want to use another lab, that’s OK. At a minimum, I need “whole-rock” data for Na, Mg, Al, Si, K, Ca, Ti, Cr, Mn, Fe, and Ni. 

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.

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. 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.

Iron Meteorites

If you have found 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. In proper hands, and XRF analyzer would be useful for iron meteorites.