This meteorite, called EETA 79001, was found on the ice in Antarctica, and is almost certainly from Mars. For scale, the cube at the lower right is 1 centimeter on a side. The meteorite is partly covered by a black glassy layer, the fusion crust. The fusion crust forms when the meteorite enters the Earth's atmosphere at high speed, with friction heating and melting the outer portion of the meteorite. Inside, the meteorite is gray. It is a basalt, very similar to basalts found on Earth. It formed in a volcanic eruption about 180 million years ago; other martian meteorites formed in volcanic eruptions about 1.3 billion years ago. This meteorite is almost certainly from Mars because it contains a small amount of gas that is chemically identical to the martian atmosphere.
NASA Johnson Space Center S80-37480