"I found a strange rock, I think it fell from space!" It's a statement geologists and museums hear every single day. While finding a genuine space rock is extremely rare, it does happen. When a meteor survives its fiery plunge through the atmosphere and hits the dirt, it is classified as a Meteorite.
If you suspect you've found a cosmic treasure out on a hike, geologists perform a few basic screening tests to weed out the "meteor-wrongs." Here are four simple tests you can do at home.
1. The Magnet Test
Over 90% of all meteorites are rich in extraterrestrial iron and nickel. Therefore, a genuine meteorite will strongly attract a magnet. If your rock is completely non-magnetic, the chances of it being a meteorite are less than 1 in 1,000.
2. The Weight Test (Density)
Due to the dense iron/nickel alloys packed inside them, meteorites are surprisingly heavy for their size. If you hold your rock in one hand, and a standard Earth rock of the exact same size in the other, the meteorite should feel noticeably heavier and denser.
3. The Fusion Crust Test
As the rock falls through our atmosphere at 40,000 miles per hour, the exterior literally melts due to extreme friction. This intense heating creates a "Fusion Crust." A fresh meteorite will look like a lump of charcoal, coated in an ultra-thin (1-2 millimeters thick), smooth, pitch-black crust that looks like black glass or burnt pottery.
4. The Streak Test
The most common Earth rock mistaken for a meteorite is Magnetite or Hematite (iron ores). You can spot these fakes by dragging the corner of the rock forcefully across the unglazed bottom of a ceramic coffee mug (like a chalkboard).
If it leaves a rusty-red or dark grey/black streak resembling a pencil mark, it is Earth iron (hematite/magnetite). A genuine meteorite will rarely leave a streak at all, or it will be incredibly faint and colorless.
The Honest Starting Point
Almost every rock brought to a university geology department as a suspected meteorite is not one. The community even has a word for them: meteorwrongs. That is not a reason to skip testing yours — genuine finds do turn up in gardens and fields — but it is a reason to run the cheap eliminating tests before you get attached to the idea.
The Five-Minute Test Sequence
Run these in order. Each one is quick, and the early ones eliminate most candidates.
- Magnet. Nearly all meteorites contain metallic iron and nickel and will attract a magnet noticeably. If a strong neodymium magnet shows no response at all, you can almost certainly stop here. A small number of rare achondrites are the exception, and they are rare enough that betting on one is not sensible.
- Streak test. Rub the specimen firmly on the back of an unglazed ceramic tile. A meteorite leaves no streak, or at most a very faint grey one. Magnetite leaves a solid black streak; hematite leaves red-brown. This single test eliminates the majority of magnetic candidates, and it is the one people skip.
- Fusion crust. A fresh fall carries a thin black rind — well under a millimetre — that is matte rather than glassy and may show fine flow lines. It weathers to rusty brown over years. It is thin: if the dark outer layer is several millimetres deep, that is not fusion crust.
- Regmaglypts. Shallow, smooth, thumbprint-like depressions where hot gas scoured the surface during entry. These are dents, not holes. Confusing them with bubbles is the classic error.
- Density. Meteorites feel wrong — noticeably heavier than an Earth rock of the same size. Stony meteorites run around 3.0-3.5 g/cm³ and irons around 7.5 g/cm³, against roughly 2.7 for ordinary granite.
- Window. If everything above passes, grind or file a small flat on one corner and examine it under magnification. Chondrites show chondrules — tiny round silicate beads — and bright flecks of free metal scattered through the matrix. Nothing formed on Earth looks like that.
What Rules It Out Immediately
| If you see... | It is almost certainly |
|---|---|
| Bubbles or gas holes (vesicles) | Slag, industrial waste or volcanic rock — meteorites do not have them |
| A solid black streak on unglazed tile | Magnetite |
| A red-brown streak | Hematite |
| Visible quartz crystals | A terrestrial rock — quartz is essentially absent from meteorites |
| Layering or banding | Sedimentary or metamorphic rock |
| Rounded, water-smoothed shape | A river cobble |
| Light for its size | Not a meteorite |
| Rust with no metal underneath | Iron ore or weathered slag |
Getting a Real Answer
If your specimen survives all six tests, do not sell it, cut it up, or clean it aggressively — and in particular do not soak it. Photograph it against a scale, note exactly where you found it, and contact the geology or earth sciences department of a nearby university; most will look at a photograph for free. Formal classification goes through the Meteoritical Society via an approved laboratory, and a classified, named meteorite is worth considerably more than an unclassified rock.
Ownership law varies by country. In some places a find belongs to the landowner, in others to the state, and exporting meteorites is restricted in a number of jurisdictions. Check before you make plans.
A Note on Where They Are Actually Found
Meteorites fall evenly over the Earth but are found where they stand out and where they survive: deserts, dry lake beds and Antarctic blue ice. In a temperate garden, a dark magnetic rock is far more likely to be a fragment of slag from a century-old forge, foundry or railway line than a visitor from the asteroid belt. That is simply where the odds sit.
