Three rock fragments taken from the moon by Soviet space missions in 1970 have been sold for $ US855,000 ($ A1.17m) at the New York auction.
Sotheby's auction house said "moonstone" was the only known lunar material documented in private hands.
They were offered for sale by unknown American private collectors who bought them at an auction in 1993 for US $ 442,500 ($ A605,000).
Sotheby's said buyers on Thursday were other private American collectors, but the name was not disclosed.
The auction house said ahead of sales that the fragments, ranging from around 2 x 2mm to 1 x 1mm, could reach $ 1 million ($ A1.37m)
The first month's sample belonged to Nina Ivanovna Koroleva, widow of the former director of the Soviet space program Sergei Pavlovich Korolev.
They were presented to him as a gift in the name of the Soviet Union in recognition of her husband's contribution to the program, Sotheby said.
The particles were taken in September 1970 by unmanned Luna-16, which drilled holes in the surface to a depth of 35 cm and extracted core samples, the auction house said in a statement.
Most of the other known samples were taken from the fixed moon with two entities that gathered them: the United States during the Apollo 11-17 and Soviet Union missions through unmanned Luna-16, Luna-20 and Luna-24 missions.
Collectors pay a large amount for space exploration artifacts. Last year Sotheby's sold a zipper bag stamped with the words "Lunar Sample Return" which was lined with moon dust used by Neil Armstrong for the first manned mission to the moon in 1969, costing US $ 1.8 million ($ A2.5m)