According to John Sorenson, copper, as mentioned in Mosiah 11:8, was well known anciently. . . One alloy used in many parts of nuclear America was tumbaga, a mixture of gold and copper. Treated properly it had the "appearance of gold" but weighed less and probably was cheaper. R. H. Putnam has argued persuasively that the Book of Mormon plates that were in Joseph Smith's hands were of tumbaga. (Had they been unalloyed gold, they would have been too heavy for a single person to carry.) A tumbaga specimen from Belize (British Honduras) shows that this material was known in the Maya lowlands no later than the fifth century A.D. [John L. Sorenson, An Ancient American Setting for the Book of Mormon, F.A.R.M.S., p. 283]