AMSTERDAM The Dutch national museum said Thursday that one of its prized possessions, a rock supposedly brought back from the moon by U.S. astronauts, is just a piece of petrified wood.

Rijksmuseum spokeswoman Xandra van Gelder, who oversaw the investigation that proved the piece was a fake, said the museum will keep it anyway as a curiosity. Its a good story, with some questions that are still unanswered. We can laugh about it.

The museum acquired the rock after the death of former Prime Minister Willem Drees in 1988. Drees received it as a private gift on Oct. 9, 1969, from then-U.S. ambassador J. William Middendorf during a visit by the three Apollo 11 astronauts, part of their Giant Leap goodwill tour after the first moon landing. The museum had vetted the moon rock with a phone call to NASA, Van Gelder said.

I do remember that (Drees) was very interested in the little piece of stone, said Middendorf, who lives in Rhode Island. But that its not real, I dont know anything about that. The U.S. Embassy in the Hague said it was investigating the matter.

The rock, which the museum at one point insured for more than half a million dollars, was worth no more than $70, according to geologist Frank Beunk. Its a nondescript, pretty-much-worthless stone.