The woman, who has not been identified, was taken into custody Thursday in Lake Elsinore as part of an undercover sting conducted by NASA investigators with the assistance of local police, the Los Angeles Times reported.
"It's possible this is a moon rock, but it has to be tested first," said Gail Robinson, deputy inspector general at NASA.
The investigation, lasting several months, led to a covert meeting in a Lake Elsinore restaurant where undercover NASA officials agreed to buy the rock for $1.7 million, a report by the Riverside County Sheriff's Department said. When the woman produced the artifact, several Lake Elsinore police investigators and NASA agents confiscated it and took her into custody.
Moon rocks are classified as "national treasures'' and federal law prohibits the sale of the artifacts.
Astronauts who landed on the moon brought back 2,415 samples of moon rocks weighing a total of 842 pounds.
Robinson said "it's not all that unusual" for someone to try to sell a piece of the moon. The space agency's inspector general's office issues a report twice a year of space objects and artifacts being sold on the black market.
A recent report detailed the recovery of two rocket motors from the Apollo program that put man on the moon that were up for sale on the Internet.