As far as can be learned from a study of the scientific contributions of Yoder (1950), Foshag (1945), and others who have dealt with the jade-jadeite problem, it appears that, although the presence of one or the other mineral has been reported from a considerable list of widely separated localities in both the Old and the New World, the exact conditions leading to their development have been subject to controversy, partly because occurrence in situ is extremely rare. The passing references to places from which the Mayans secured their supplies of raw material are in general vague, based on hearsay or traditional accounts, combined with inferences relating to the abundant artifacts unearthed at classical sites.