METEORITE OR METEORWRONG?

streak

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 meteorite.
 

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.

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.


www.catchafallingstar.com
www.catchafallingstar.com


Prepared by:

Randy L. Korotev


Department of Earth and Planetary Sciences
Washington University in St. Louis


Please don't contact me about the meteorite you think you’ve found until you read this and this.

e-mailkorotev@wustl.edu