If the plates were gold plates of the dimensions indicated they must have weighed between 175 and 225 pounds. (Whalen, 27.)
Joseph, however, gave the dimensions which he saw and the witnesses gave the approximate weights which they hefted. Joseph described the plates as having the appearance of gold. Turning to the New World we find that the ancient inhabitants did indeed make engravings upon a metal which was lighter than gold but had the appearance of gold.
Heather Lechtman, in a 1984 article in Scientific America, addressed the recent discovery of several large metal objects in South America. Most of these objects were made out of hammered sheet copper. When these copper sheets were first unearthed they were covered with a green corrosion. Once the corrosion was removed, however, they discovered that the copper had originally been covered with a thin layer of silver or gold so that these sheets appeared to be made entirely out of those precious metals.... (Lechtman, 56.) Lechtman explains that the most important alloy discovered at these South American sites was a mixture of copper and gold known as tumbaga. When copper and gold (the only two colored metals known to man) are melted together they mix, and stay mixed after they cool and solidify. This alloy was known not only in South America, but in Mesoamerica as well. (Ibid., 60.) Tumbaga ranged from 97 percent gold to 97 percent copper with traces of up to 18 percent of other metals, impurities, or silver. Once the gold finish was applied to the tumbaga it would appear to be made of solid gold. Putnam explains that tumbaga the magic metal, can be cast, drawn, hammered, gilded, soldered, welded, plated, hardened, annealed, polished, engraved, embossed, and inlaid. (Putnam, 789, 828-829.) Nevertheless, tumbaga will destroy itself if it is not stored properly. It is therefore interesting to note that the Book of Mormon plates were laid atop two stones which lay across the bottom of the stone box so that the plates would not be exposed to water or dirt.
Too little gold in the Book of Mormon plates would have made them brittle, and too much gold would have made them too heavy as well as increasing the danger of distortion during engraving. Thus, according to Putnams calculations, the Book of Mormon plates (which were probably tumbaga) were between 8 and 12 carat gold and thus would have weighed between 53 and 86 pounds. To the eye, however, the tumbaga plates would have had the appearance of pure gold. (Ibid., 830, 831.)
The research of Robert F. Smith reveals that if the plates were made of the tumbaga alloy, other details fit into place. Take the color of the plates: The plates are consistently described as gold and golden. When tumbaga (which is red) is treated with any simple acid (citric acid will do), the copper in the alloy is removed from its surface leaving a brilliant .0006 inch twenty-three karat gilt coating. Indeed, this process was used in ancient America. Plus, this surface covering is much easier to engrave. Likewise, pure gold would be too soft to make useful plates. But tumbaga is remarkably tough and resilient.... (Robert Smith, 276.)
Not only did Joseph Smith hit the nail on the head with the claim that the Book of Mormon was engraven upon metal plates, but the Nephites could have chosen no better material to vindicate their sacred scripture than tumbaga which has the appearance of gold.
Michael R. Ash
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