Dramatic stone masks, iconic finds in the ancient Mexican city of Teotihuacan, were supposed to be made from a jadelike stone. Many researchers also thought the large faces were made on the site of the pre-Columbian metropolis. Instead, they seem to have been made in workshops a great distance to the south of the city. And they are made of softer stone like serpentinite and polished with quartz. Quartz does not appear around Teotihuacan, bolstering the notion that the masks were made far away. “Almost everything that has been written about the making of the Teotihuacan masks is untrue,” says Jane Walsh, an anthropologist at the Smithsonian National Museum of Natural History in Washington, D.C.