Mormon's Heavy Metal

One criticism of the Book of Mormon is that the plates that Joseph Smith found would have been way too heavy. The argument is described here.

The gentleman in this video actually makes some valid points. Joseph Smith says, "engraven on plates which had the appearance of gold, each plate was six inches wide and eight inches long and not quite so thick as common tin.... The volume was something near six inches in thickness...."(Joseph Smith, Times and Seasons, v3:9, March 1, 1842, 707.)

If the plates were the indicated size, represented by his replica, then it would have been much too heavy for Joseph to carry. Many people don't realize this, but gold is actually denser than lead, and therefore heavier. Many critics of the Book of Mormon claim that the plates would have had to weigh a little over 200 lbs., and that's actually pretty accurate. A solid gold block of 288 cubic in. would weigh just over 200 lbs.

However, William Smith, a brother of the Prophet who had handled and hefted the plates in a pillow-case, claimed on several occasions that the set of plates weighed about sixty pounds, as did Willard Chase, while Martin Harris said that they weighed forty to fifty pounds.

So how do we answer this criticism? The math is legitimate. The science is sound. Solid gold would weigh much more than Joseph Smith claimed.

The problem is that the plates were not solid gold.

First of all, it was not solid. There is a difference between a solid block and a stack of plates, especially engraved plates. In his article, “Were the Golden Plates made of Tumbaga?”, Read H. Putnam says,

"A solid gold block of totaling 288 cubic inches would weigh a little over 200 pounds.... But the plates would weigh much less than a solid block of the same metal. The unevenness left by the hammering and air spaces between the separate plates would reduce the weight to probably less than 50 percent of the solid block."

But in addition to not being solid, the plates were also not gold, though they probably had gold in them. Joseph Smith never says that the plates are made of pure gold. He merely says that they "had the appearance of gold." This may sound like word twisting, but this interpretation is supported by the statments of others close to Joseph.

For example, William Smith, Joseph's brother, said that he understood the plates to be "a mixture of gold and copper". Other early church leaders gave other guesses regarding the composition of the plates. So while we may not know what exactly the plates were, and early church leaders could only guess, we do know that it is clearly not solid gold.

Heather Lechtman, in a 1984 article in Scientific America called "Pre-Columbian Surface Metallurgy", 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 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.

Example of Tumbaga

 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.” 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 Putnam’s 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.

 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....”

So not only was the account of Joseph Smith plausible after all, but it was actually startlingly accurate, considering recent archaeological discoveries.