Gleamite

How to identify a meteorite

By The Gleamite desk, Identification research · updated

Meteorite identification is honest elimination. Most candidates fail four free checks — a magnet response without a black streak, unusual weight, a thin dark fusion crust, and no gas bubbles anywhere. What passes deserves photographs and a university lab, because no home test confirms a meteorite; home tests only retire the impostors.

The four checks, cheapest first

  1. Step 1Pass a magnet over itMost meteorites carry iron-nickel and respond. No response at all makes the candidacy unlikely; a response keeps it alive without proving anything.
  2. Step 2Heft itMeteorites run heavy for their size — iron ones dramatically so. A stone that feels normal or light is almost certainly terrestrial.
  3. Step 3Look for the crust and the dentsA thin, dark rind — fusion crust — sometimes with shallow thumbprint dents called regmaglypts. Fresh crust can show flow lines; old finds wear it down to patches.
  4. Step 4Apply the vetoesGas bubbles, visible layers, or a black or red-brown line on a streak plate each end the candidacy. Meteorites are solid, unlayered, and streak faintly or not at all.

The streak veto does double duty. Drag the stone across unglazed tile: magnetite draws a black line and hematite a red-brown one, and those two minerals — both magnetic-ish, both heavy, both dark — are the natural rocks most often carried into labs. A magnetic stone that leaves no streak stays interesting; the streak mechanics are on the streak test page.

Bubbles are a veto. Fusion crust forms on solid rock falling through air; slag and scoria foamed as they cooled. A candidate with gas holes is not a meteorite, whatever else it does right.

Slag, the great impostor

University identification services report that nearly all public submissions are meteorwrongs, and the champion is industrial slag: furnace waste that is dark, heavy, often magnetic, and glassy enough to look otherworldly. Its tells are the bubbles, streaky green-to-black glassy color, and geography — slag concentrates near old smelters, rail lines and fill dirt, which is why the copper-country beaches in Michigan rock identification produce so many convincing fakes. Volcanic scoria fails the same way, and glassy candidates without bubbles usually turn out to be the natural glass covered in how to identify obsidian — sharp, light, and not magnetic at all.

A round, light-for-its-size candidate fails in the opposite direction: hollow means geode, and that is a happier outcome than most.

What confirmation actually takes

Home checks only eliminate; they never confirm. Real confirmation is laboratory work — a cut face showing metal flecks or chondrules, nickel analysis, sometimes an isotopic signature — done by university geology departments and dedicated meteorite labs, several of which screen photos free before asking for a sample. Skip the folk tests entirely: grinding off the crust destroys the most diagnostic surface, and acid experiments add hazard without adding certainty.

If the find passes every check, treat it like the valuable object it might be — confirmed meteorites sell by the gram — which means photographs first, minimal handling, and the elimination discipline of how to identify valuable rocks: spend nothing on testing that a free photo screening could settle. The base rate is brutal and worth respecting; the stones that beat it are the reason the checks exist.

Questions people ask

How can I tell if a rock is a meteorite?
Run the elimination checks. Most meteorites attract a magnet, feel unusually heavy for their size, and wear a thin dark fusion crust, sometimes with thumbprint-like dents. Just as important is what they lack: gas bubbles, layers, and a colored streak. A candidate passing all of that is worth showing to a university lab — the only place confirmation actually happens.
What is most often mistaken for a meteorite?
Industrial slag and magnetite-rich Earth rocks, by a wide margin — university identification services report that nearly all public submissions are these meteorwrongs. Slag betrays itself with gas bubbles and streaky glassy color; magnetite and hematite betray themselves on a streak plate, drawing black or red-brown lines that meteorites do not leave.
Do all meteorites stick to a magnet?
Most do — iron meteorites strongly, stony chondrites noticeably, because both carry iron-nickel metal. A few rare types respond weakly, but for a beginner the practical rule holds: no magnet response at all makes a meteorite very unlikely, while a strong response alone proves nothing, since magnetite and slag respond too.
Where can I get a suspected meteorite checked?
University geology departments and dedicated meteorite laboratories examine finds, and several screen photographs at no charge before asking for a sample. Send sharp photos in daylight with a coin for scale, note the find location, and expect the honest base rate: identification services confirm only a tiny fraction of submissions.
The Gleamite deskWrites every identification chart on this site from named mineralogical properties — Mohs values, streak colors, specific gravity — sourced from USGS and standard references on a stated date, and runs the same hardness, streak and vinegar checks it tells readers to run.
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