A rock named Blue Genesis was brought back from the moon by Apollo 16, the final moon mission, in 1972. Moon rocks remain rare and precious for that a single reason - because we never went back for more.
The astronauts brought it and 200 pounds of other rocks back to Earth as the bounty from Apollo 16. At the Lunar Receiving Laboratory in Houston, scientists ascertained that Blue Genesis, as it was once called, weighed 12 pounds, and they cut it to pieces to send out for study. Geologists estimate that it could be 4.23 billion years old.
Since 1981, a sliver of that rock has resided like a wedge of old cheese — a light gray speckled filling inside a dark rind — at the American Museum of Natural History in Manhattan.
From the Upcoming ueue, submitted by healthylivinggal83.
http://en.wikipedia.org/wiki/Apollo_17