Have you ever seen those stunning skulls carved out of rock crystal? They are in a number of major museums. I think I saw the one at the British Museum and the Smithsonian National Museum of Nat'l History also has one. Here's the scoop:
For some 60 years, tall tales about crystal skulls have circulated, beginning with a colorful British banker/adventurer who said that during the 1920s he and his daughter discovered a crystal skull under the altar of a Mayan temple. He claimed it was 3600 years ago with supernatural powers and that Mayan priests wielded it to invoke gods and devils. Its curse could bring misfortune and death!
However, Jane Walsh, an anthropologist at the Smithsonian's National Museum of Natural history says that no one has ever excavated a carved crystal skull. And that "if you were a pre-Columbian artisan and you wanted to carve something in stone or rock crystal -- which is actually quartz -- you'd use a stone file with maybe sand as an abrasive... Modern stone carving tools have embedded abrasives and leave very different imprints in the stone."
Bottom line: Walsh says: we discovered that all of the crystal skulls had been carved with modern coated lapidary wheels using industrial diamonds and polished with modern machinery." The Smithsonian's is no longer on view! (from Inside Smithsonian Research Summer 2005)