A Martian meteorite is a rock that formed on the planet Mars and was then ejected from Mars by the impact of an asteroid or comet, and finally landed on the Earth. Of over 61,000 meteorites that have been found on Earth, 224 were identified as Martian as of January 2019. These meteorites are thought to be from Mars because they have elemental and isotopic compositions that are similar to rocks and atmosphere gases analyzed by spacecraft on Mars. In October 2013, NASA confirmed, based on analysis of argon in the Martian atmosphere by the Mars Curiosity rover, that certain meteorites found on Earth thought to be from Mars were indeed from Mars.
The term does not refer to meteorites found on Mars, such as Heat Shield Rock.
On January 3, 2013, NASA reported that a meteorite, named NWA 7034 (nicknamed "Black Beauty"), found in 2011, in the Sahara desert, was determined to be from Mars and found to contain ten times the water of other Mars meteorites found on Earth. The meteorite contains components as old as 4.42 ± 0.07 Ga (billion years), and was heated during the Amazonian geologic period on Mars.