Short answers, pulled from the story.
Operation Lunar Eclipse was a 1998 federal undercover sting operation run by NASA's Office of Inspector General to catch people selling counterfeit or stolen Moon rocks. It recovered the Honduras Goodwill Moon Rock, a 1.142 gram sample that Florida businessman Alan H. Rosen was attempting to sell for five million dollars. The rock was seized from a Bank of America vault and formally returned to Honduras in September 2003.
Approximately 180 of the 270 Apollo 11 and Apollo 17 Moon rocks given to nations of the world by the Nixon Administration are unaccounted for. Many of the rocks that are located have been locked away in storage for decades rather than put on public display.
Joseph Gutheinz is a retired NASA Office of Inspector General Senior Special Agent who led Operation Lunar Eclipse in 1998. After leaving NASA for a teaching position at the University of Phoenix in Arizona, he created the Moon Rock Project starting in 2002, assigning criminal justice graduate students to track down missing goodwill Moon rocks given to states and nations by President Nixon. Hundreds of students have participated from 2002 to the present.
Interns Thad Roberts and Tiffany Fowler stole 101 grams of Moon rocks from the Johnson Space Center in June 2002, along with accomplices Gordon McWhorter and Shae Saur. They used knowledge of the security systems gained during their internship to remove a 272-kilogram safe from building 31 North. All were arrested on the 20th of July 2002 after Roberts advertised the rocks on a Belgian mineralogy club website, and the samples were recovered. The theft was the subject of Ben Mezrich's 2011 book Sex on the Moon.
The rock displayed by Amsterdam's Rijksmuseum as a lunar sample was confirmed in August 2009 to be a piece of petrified wood. The museum had acquired it after the death of former Dutch prime minister Willem Drees in 1988. Drees received it on the 9th of October 1969 as a private gift from US ambassador J. William Middendorf during the Apollo 11 astronauts' "Giant Leap" goodwill tour. Geologist Frank Beunk described it as "a nondescript, pretty-much-worthless stone."
Spain received both Apollo 11 and Apollo 17 Moon rocks, but both went missing after being given to Franco's administration by the Nixon Administration. The Apollo 17 rock ended up with the family of Admiral Luis Carrero Blanco and was donated to the Naval Museum in 2007. Spain's Apollo 11 Moon rock remains unaccounted for; Franco's grandson told a Spanish newspaper in July 2009 that it likely went missing during a family move, and students assigned to the Moon Rock Project were searching for leads in Switzerland.