Streak

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A type of rock that people often mistake for meteorites are those composed of iron oxides like hematite and magnetite because such rocks are denser than most common rocks. Hematite and magnetite can be recognized by the streak test.

If a rock leaves a streak like this, it is not a meteorite.

Streak is a word referring to the color of the streak that a rock makes when it is scraped against the unglazed (rough surface) side of a white ceramic tile or the unglazed bottom of a white coffee cup or toilet tank cover. Hematite makes a rust or blood-red colored streak; magnetite makes a dark gray streak. Hematite and magnetite streaks are easy to make, almost like chalk on a sidewalk.

Another test for hematite is that when a hematite-rich rock is cut with a rock or tile saw, the wash water turns bright rusty red. Alternatively, file it with a tool file. If there is reddish powder on the file, then the rock is hematite. Some iron oxide-hydroxides (goethite, akaganéite, and lepidocrocite) also leave a red streak.

Note the rusty red powder on the file. The rock is a hematite concretion.

Meteorites give no streak or a weak grayish streak, but only if you press hard. Also, any terrestrial igneous rock will not give a streak, so absence of a streak does not indicate that the rock is a meteorite.

In the U.S., nearly all barns are painted red with paint that contains hematite because hematite is abundant and, consequently, the cheapest paint pigment.
Most of the “red rocks” of the American Southwest are hematite-cemented sandstones.
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