What are meteorites made of?

Meteorites are made of rock or metal. They enter the earth's atmosphere at speeds of at least 11 km per second, which makes them glow brightly. Several thousand meteorites enter the earth atmosphere every year, but very few of them reach the ground. The largest known meteorite is made of iron and weighed 66 tonnes. It probably fell to the earth in prehistoric times in what is now Nambia, Southwest Africa. In general, it is hard to find meteorites. Recently, researchers have been locating them on the ice sheets in the Artic and the Antartic, where they are easier to find.