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.
Streak is a
word referring to the color of the streak that a rock makes when it is
scraped against the unglazed 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.
If you get a
red streak or a gray streak like those in the photo, the rock is not a
“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.
Meteorites give no streak or only 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.