Three fragments of rocks retrieved from the moon by a Soviet space mission in 1970 were sold for $855,000 at a New York auction on Thursday.
Sotheby's auction house said the "moon rocks" are the only known documented lunar matter in private hands. They were offered for sale by an unidentified private American collector who purchased them at auction in 1993 for $442,500.
Sotheby's said the buyer on Thursday was another private American collector, but the name was not disclosed.
The auction house said ahead of the sale that the fragments, ranging in size from about .079 inch x .079 inch (2 x 2mm) to .039 inch x .039 inch (1 x 1mm), could fetch up to $1 million.
The lunar samples originally belonged to Nina Ivanovna Koroleva, the widow of former Soviet space program director Sergei Pavlovich Korolev. They were presented to her as a gift on behalf of the Soviet Union in recognition of her husband's contributions to the program, Sotheby's said.
The particles were retrieved in September 1970 by the unmanned Luna-16, which drilled a hole in the surface to a depth of 13.8 inches (35 cm) and extracted a core sample, the auction house said in a statement.
Most other known samples taken from the moon remain with the two entities that collected them: the United States during the Apollo 11-17 missions and the Soviet Union via the unmanned Luna-16, Luna-20, and Luna-24 missions.
Collectors pay huge sums for space exploration artifacts. Last year Sotheby's sold a zippered bag stamped with the words "Lunar Sample Return" laced with moon dust which was used by Neil Armstrong for the first manned mission to the moon in 1969, for $1.8 million.