Residents of Deming, N.M., have learned that mysterious sounds heard this month were explosions from Playas carried 75 miles by atmospheric conditions.

Playas, formerly dominated by the Phelps-Dodge Copper Co., is now run as a testing center by the New Mexico Institute of Mining and Technology. Activities there include training for law enforcement and other first responders and for Border Patrol agents.

Van Romero, the institute's vice president for development and technology, said the explosions come from a contract the center has to produce industrial diamonds for cutting. The process involves placing carbon in a pipe, which is then buried, and explosions are used to convert the carbon into diamond.

Romero said the blasts are not other-worldly or sinister, although the diamond production process does have a magic quality.

When the blasts were first heard in Deming, there were rumors the Air Force was involved in some sort of top-secret activity.