Michael De Groote, “How Gold were the Golden Plates?” mormon tmes.com, July 7,2010

“For we have seen and hefted, and know of a surety that the said Smith has got the plates.” (From “The Testimony of Eight Witnesses.”)

Thud. If you dropped the golden plates, they would have made a pretty big dent in the floor — or worse, they probably would have crushed your foot. Joseph Smith carried them around, hid them in a log, a bean barrel, boxes and under hearthstones. They were picked up and fingers flipped through the metallic leaves, frrrrrrp! Emma Smith had to move them out of her way occasionally while doing housework.

The golden plates were just so — tangible, physical and, well, real. But just how big were they? How much did they weigh? How many plates were there? What were they made of?

Joseph Smith wrote in the Wentworth Letter that the plates were “six inches by eight inches long.” Martin Harris and David Whitmer remembered 7 by 8 inches. Joseph Smith wrote that the plates were “something near six inches in thickness.” Harris remembered it being about four inches.

Take Joseph Smith’s estimate (sorry, Martin) of 6 inches by 8 inches by 6 inches, and that gives us 288 cubic inches. Metallurgist Read H. Putnam, in an Improvement Era article in September 1966, wrote that a “solid block of gold totaling 288 cubic inches would weigh a little over 200 pounds.” But, of course, the plates were not a solid block.

The individual plates were not perfectly shaped. “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,” Putnam wrote.

That gives us about 100 pounds. Not impossible to move around, but still pretty heavy.

But the plates were not likely made of pure gold. The Book of Mormon merely says they were made of “ore” 1 Nephi 19:1. (See also Mormon 8:5.)

The Eight Witnesses described them as having “the appearance of gold.”

Pure gold would be too soft to use anyway.

“The metal would need to be soft enough at the surface to accept the engraver’s tool, yet firm enough in the center to keep the plate from distortion under the pressure; it would also have to be smooth enough for the lines and figures to retain their proportions,” Putnam wrote. In other words, the plates, if they were to match their description, had to be an alloy.

As it turns out, ancient Americans used an alloy of gold and copper — the two colored metals. The Spaniards called this metal alloy “tumbaga.” Properly made, a plate of this alloy would have the right properties for engraving and would also look like ordinary gold. But it would also weigh less. Putnam estimated a solid block of the ideal engraving-friendly copper/gold alloy would weigh about 107 pounds. Take half of that away to account for air between the plates and “the weight of the stack of plates would be about 53 pounds.”

Putnam wrote that the weight would be higher as the ratio of gold to copper went up.

Just for contrast, a block of sand that size would be about 17 pounds, a solid block of granite about 29 pounds.

It shouldn’t be a surprise then to learn that witnesses put the weight of the plates at about 60 pounds. Harris said “from forty to sixty lbs.” William Smith said “about sixty pounds.”

William Smith also said the plates were “a mixture of gold and copper” — the precise alloy that Putnam found was used by ancient Americans.

Putnam calculated that each plate could have been .02 inches thick (average copier paper is five times thinner or about .004 inches thick). Emma Smith said, “They seemed to be pliable like thick paper, and would rustle with a metallic sound when the edges were moved by the thumb, as one does sometimes thumb the edges of a book.”

By judging how much space a plate would take in a stack, Putnam deduced it would be about 20 plates to the inch. “The unsealed portion (one-third of the whole) would then consist of 40 plates or 80 sides.”

Only 80 sides for the whole Book of Mormon — plus the lost Book of Lehi? In an April 1923 issue of the “Improvement Era,” Janne M. Sjodahl proved that 14 pages of the Book of Mormon could be written in Hebrew in a space that was only 7 by 8 inches. “That is to say, the entire Book of Mormon … could be written on 40 3/7 pages — 21 plates in all.”

John Gee, senior research fellow at the Neal A. Maxwell Institute for Religious Scholarship at BYU, reexamined Sjodahl’s article in 2001 and concluded that the small characters used in Sjodahl’s experiment are similar in size to actual Hebrew characters engraved on ancient objects found in Israel.

When you take into consideration that the plates were engraved in space-saving reformed Egyptian, because, as Moroni wrote, “if our plates had been sufficiently large we should have written in Hebrew,” there appears to be room to spare (See Mormon 9:33).

Just don’t drop them on your foot.

In addition to the articles mentioned in the text, this column was based on information found in “Journal of Book of Mormon Studies,” Volume 10, Number 1.