DENVER -- A moon rock missing for decades was located Tuesday.

It turns out it is at the home of a former Colorado governor.

The search for the moon rocks, given to the governors of all 50 states in 1974, picked up recently when a retired NASA employee -- now a professor at the University of Phoenix -- gave his students an assignment to track them down.

About half of the 50 moon rocks are missing.

7NEWS decided to call former Gov. John Vanderhoof to find out if he remembered what happened to the moon rock plaque presented to him by NASA astronaut Jack Lousma on Jan. 9, 1974.

"Well Governor, what do you know about these moon rocks? Where are they?" asked 7NEWS reporter Russell Haythorn.

"They're in my house, in my display of things," he told 7NEWS.

Vanderhoof, 88, said he didn't know what to do with the display once he left office so he simply decided to take it with him.

"My recollection is that someone gave me a plaque and said, 'This is for you.' It wasn't that big a deal back then," Vanderhoof said.

He also told 7NEWS he did not know it was worth $5 million on the black market.

The moon rock is displayed in a golf-ball sized acrylic button mounted on a plaque. The plaque also contains a miniature Colorado flag carried to the moon on the Apollo 17 mission.

Vanderhoof said the plaque is hanging on a wall in his home office.

"They can take it if they want it," Vanderhoof said. "I don't guess I need it."

Three months after Apollo 17 returned home in December 1972, then-U.S. President Richard Nixon ordered the distribution of fragments from a lunar rock collected on the mission to 135 foreign heads of state and to the 50 U.S. states and its provinces.

There is also lunar rock displayed at the Colorado state Capitol building and in the Denver Museum of Nature and Science.

According to the Denver Museum of Nature and Science, the museum’s sample is also a fragment of a melon-sized rock returned by Apollo 17 astronauts.

It took well over a year for the museum to formulate a security plan that was approved by NASA before the museum was allowed to accept the lunar sample for display.

Such high security is not out of the ordinary for many museums, but it does demonstrate how seriously NASA takes the dissemination of these national treasures.

The 842 pounds of lunar samples returned by the Apollo missions are still kept at the Johnson Space Center in Houston

Missing Moon Rock Found At Former Governor's Home