The first Lunar Meteorite was discovered in 1982 in Antarctica. Meanwhile more than two dozens other different meteorites from moon are known. By comparing the mineralogy, the chemical composition, and the isotopic composition between lunar meteorites and samples from moon, collected by Apollo missions, the origin from moon is ascertained.
Lunar meteorites are launched from moon by large impacts. Until now, no single crater could be identified as origin of lunar meteorites. For statistical reasons, the compostion of lunar meteorites is closer to the average composition of the lunar surface material than the composition of the samples from Apollo and Luna missions. Apollo and Luna samples are from a relatively small area on the nearside of the moon, whereas lunar meteorites possibly also samples material from the farside of the moon.
When the first meteorite from moon was discovered in 1982 this lead to new speculations that there could also exist meteorites from mars. In fact, the first martian meteorite was identified in the same year. There are also speculations about the possibility to find "earth meteorites" on the surface of the moon. This would be very interesting because in this case stones from earth older 3.9 billion years, which are destroyed on earth by various geological processes, may have survied on moon. Thus some scientists propose new missions to moon to search for ancient rocks from earth on the moon.
wikipedia.org dumped 2003-03-17 with terodump