In the same _Crónica_ we read that Montezuma, who succeeded Ahuitzotl after his death in 1502, received a royal tribute from his vassals in Xaltepec, a coast town of Tehuantepec, among which were “broad collars [_sic_] for the ankles, strewn with gold grains and very rich stone mosaic-work.”[25] [Illustration: PL. V MASK OF WOOD WITH MOSAIC DECORATION BRITISH MUSEUM, LONDON] SOURCE OF TURQUOIS The source of the considerable quantity of turquois used in Mexico in pre-Spanish times for personal ornaments and mosaic incrustation is still an unsolved problem. Thus far no prehistoric workings have been found in Mexico. Only recently turquois has been discovered at the silver mines at Bonanza, Zacatecas, but Dr. Kunz, who has called our attention to this, writes that he has no information regarding prehistoric workings there.[26] In the extensive bibliography on the geology of Mexico by Aguilar y Santillan[27] we find only a single entry for turquois, that being the study of Mexican mosaics in Rome by Pigorini.[28] Pogue[29] writes that there are no important turquois deposits that do not show signs of prehistoric exploitation, and he is also of the opinion that it is very difficult to trace the source of the turquois used by the Indians of ancient Mexico and Central America. Pogue’s conclusion is that “as no occurrence at all adequate as an important source has been discovered south of the present Mexican boundary, it therefore seems probable that the Aztecs and allied peoples, through trade with tribes to the north, obtained supplies of turquois from the Cerrillos hills [New Mexico] and perhaps other localities of the Southwest.” Sahagun is the only early chronicler who affords information concerning this point. He writes explicitly that “the Toltecs had discovered the mine of precious stones in Mexico, called _xiuitl_, which are turquoises, which mine, according to the ancients, was in a hill called Xiuhtzone, close to the town of Tepotzotlan [State of Hidalgo].” We will quote other statements by Sahagun concerning turquois: