The Metallurgical Plausibility of the Gold Plates

For six weeks in the summer of 2011, researchers convened at the Maxwell Institute to discuss the topic “The Cultural History of the Gold Plates.” The seminar was sponsored by the Mormon Scholars Foundation, hosted by the Maxwell Institute, and directed by Richard Bushman.The Summer Seminar Working Papers 2011 were presented at a BYU symposium on August 18, 2011. Working papers are unpublished, unedited, unpolished drafts. They do not necessarily reflect the views of the Maxwell Institute or BYU.


Emma said the golden plates “rustled.” She said they would make a “metalic [sic] sound when the edges were moved by the thumb, as one does sometimes thumb the edges of a book.”1 The eight witnesses said they had “the appearance … of curious workmanship.”2 William said the characters were “cut into the plates with some sharp instrument.”3 David said half the book was solid as wood.4 Martin said they were four inches thick.5 Orson said they were six.6 Joseph said they had “the appearance of gold.”

From this myriad of often contradictory descriptions, readers extract some basic vision of the plates themselves. Like a detective with an underdeveloped polaroid, believers must face the rational questions: How were the plates made? What were they made of?

I will only discuss the tamer cousins of these questions, the questions dealing with the plausibility rather than the actuality of the plates: Could plates like those described have been made? How? With what materials and what technology? I am just trying to explore the feasibility.

My presentation consists of three main parts. First, I will introduce a material for the plates. Second, I will propose a possible solution to the question of how Mormon made the golden plates. Third, I will discuss a few other notable ancient plates. Following these three sections I will suggest a few conclusions and give a few final thoughts.

Part 1 – Material

Let me begin this section by laying out the three main requirements for the plates. First, the plates need to be made of something that was available to Mormon and his fellow plate makers. Second, the plates need to look like gold. Third, the plates’ weight needs to fit the descriptions given by those who lifted them.

Given the accounts of heavy gold-looking plates, the initial hypothesis is that they are gold. This idea is disassembled in short order however due to the problem of the weight. Gold plates would just be too heavy. For example, let’s say that the plates were 6” x 6” x 8” as most witnesses said. Even if the air space between the pages was equal to the thickness of one plate, then the plates would weigh about 100 lbs. Given the number of people who report lifting the plates without throwing out their backs, and the stories of Joseph fending off his evil foes whilst tramping around with the plates force us to reconsider.

From here I shifted to the idea that the plates were not actually 24kt gold, but rather were a gold alloy, in the same way that we nowadays call even 14kt gold just gold. Mixing gold with something lighter like copper would alleviate the weight issue. If the plates were as I just described, 6” x 6” x 8” with half the volume taken up by air spaces, and it were made of 75% copper and 25% gold, then it would weight 60 lbs, just as William Smith suggested.7

Conveniently enough, archaeologists have discovered widespread use of just such an alloy in the ancient Americas. When the Spanish came to the Americas they confused this alloy with real gold because it had been treated to look just like gold. It was they who gave this set of alloys the name tumbaga.8 In the words of Heather Lechtman, a specialist in ancient metallurgy, “The tumbaga alloys … swept through the Americas from Peru to Mexico and were in common use in that entire region when the Spaniards invaded Central and South America in the 16t century. They constitute the most significant contribution of the New World to the repertoire of alloy systems…”9 Tumbaga is composed of copper, gold, and generally some lesser amount of silver. The weight of the plates is entirely dependent on the composition of the particular tumbaga alloy one chooses, as well as the dimensions that are settled upon, the space between each of the pages, and the characteristics of the rings binding them. Like I said earlier, a copper rich gold alloy would suitably bring the weight of the plates into a more realistic range. Thus, due to its weight and several other features which I will discuss later, tumbaga is the material of choice which I have adopted for this paper. 10

Before moving to section two, I should note that I will assume for the purposes of this paper the currently accepted geography for the Book of Mormon, in the southern part of Mexico, namely the area of Tehuantepec.

With this material in mind, we move to section two of the paper, the creation of the plates.

Plates Creation Process:

In this section I would like to present a theory for how Mormon could’ve made the plates. The process is by no means a definitive plan, rather one of many methods that could’ve been used, with some explanation of how the steps could have differed. I’ve sectioned the plan into six general steps: first, mining, second, alloying, third, sheet metal processing, fourth, engraving, fifth, gilding, and sixth, binding the plates together.

This first step, what I’ve termed “mining,” really involves several steps including finding the metals or ores required, extracting the desired elements, and then processing them. Finding, or technically termed “winning” the ore, is dependent on the skill of the miner to recognize valuable ores by visual indications as well as the availability of the ores in the area. Though Mormon’s particular location in southern Mexico is at least not currently one of the country’s major mining centers for the metals in question, it is likely that gold, silver, and copper would all have been available to him in less than industrial quantities.11

Gold, is generally found native, meaning it is relatively pure and not chemically combined in a compound. However the gold is often found as electrum, a mineral composed of gold and silver. This can explain the presence of silver commonly found in tumbaga and gold artifacts: it is not necessarily a purposeful addition to the gold, it was just a natural inclusion in the gold. Electrum, the gold and silver mix, was usually not refined after being mined.

Copper on the other hand was produced from a variety of copper rich ores, such as chrysocolla, azurite, malachite, or chalcopyrite as well as from the occasional deposit of native copper. These ores must be removed and then crushed. The extraneous bedrock must be removed, and then the concentrated ore is smelted. Copper smelting usually involved heating the ore to extreme temperatures in the presence of charcoal.12The carbon thus chemically reduces the oxidized ores leaving pure metals behind which can be separated mechanically from the floating slag byproducts.1314

From the mine we move to step number two, the alloying of the tumbaga. Mormon melts the two materials (electrum and copper) together at a temperature of about 1100C. The liquid elements naturally diffuse together to form the tumbaga alloy. Tumbaga artifacts range greatly in composition. Generally though they contain from 5 to 20% silver by weight, the rest being copper and gold.15 Usually there is at least 20% by weight of gold. If the alloy is too copper rich the gilding becomes very difficult and the alloy is more susceptible to corrosion.16 In one set of tumbaga artifacts from the Moche culture (c 300 A.D.) the copper content ranges from 21 to 66 wt.%.17. It’s difficult for me to say what particular alloy Mormon would’ve used, given the wide range that the archeology presents.

Though this artifact in question dates to around 300 A.D., some sources date the major usage of tumbaga to around 500 A.D. in Peru, and even later in Colombia and the Caribbean.18 Since Andean metalworkers of Peru were among the most advanced they were the starting point for much metallurgical innovation. Thus even if we are willing to give Mormon the benefit of the doubt and say he could’ve know about tumbaga working in 400 A.D., it seems significantly less likely that Nephi worked with this alloy 1000 years earlier. Fortunately this doesn’t jeopardize the heart of my argument since Mormon crafted the majority of the plates that Joseph Smith received with only a small, potentially different section from Nephi’s small plates.

In the third step Mormon takes a nice ingot of tumbaga, or maybe just a molten blob of it, and turns into rectangular sheets less than a millimeter thick. He has two main options for this process, either casting or hammering. If he takes the first option, of casting, he would use the ancient practice of lost wax casting. He would create a ceramic mold from a wax model, heat the mold to at least the melting temperature of the alloy to allow for easy liquid flow, and then pour in the melted metal.19 If he hammers the plates then he would take a piece of tumbaga and simply smash it with a hammer for a day or two.

In step four, the gilding, the real magic of the tumbaga hypothesis becomes evident. In a simple two-part process, a piece of tumbaga can actually be gilded with gold. First, the whole sheet is heated. This causes the surface to oxidize leaving a layer of copper oxide, rust. Then the sheet is soaked in a dilute acid solution which dissolves the copper oxide leaving behind just the gold and silver in a very fine layer on the surface. This process is entirely feasible for someone like Mormon to execute. The oxidizing occurs quickly even at rather low temperatures, and acid could be easily procured from certain plants or from stale urine. This fine surface layer of gold and silver would protect the plates from serious corrosion over time, and give a true golden appearance to them.

After producing the plates Mormon would need to engrave his abridgement on them, step five. He could’ve done this by indenting the words into the shape of the sheet metal in well-formed impressions. However this would not work on both sides because the impressions would be in relief on the opposite side. So if the plates were written recto-verso as John Whitmer and Orson Pratt described20, then the characters would have been scratched or incised into the metal with a sharp tool, probably of a stone or a hardened copper alloy.

Finally Mormon would need to bind the plates together. The witnesses describe the plates being held together by three metal rings that were threaded through holes punched in the pages. Martin Harris reported the rings as silver,21 while David Whitmer says they were gold,22 so it is difficult to determine their material. However, given that the ancient Peruvians knew how to weld using gold, and simple rods could easily be cast, it does not seem impossible to create gold D-rings for the binding.23

Through these six steps it is possible to lend some believability to the idea that Mormon could have made gold plates. Through the contradictions in the descriptions, the issues of chronology and geography, and the appallingly low-tech circumstances, I have found significant faith in the metallurgy of the plates.

Other Ancient Plates:

besides thinking out the process that Mormon would’ve used to create plates, and demonstrating the technological feasibility of that process, it is instructive to situate such the golden plates within the context of ancient plate making. Illustrating the precedent of making metal plates and writing on them lends a sense of probability to the discussion of plausibility. The following discussion is in no way comprehensive; it is simply meant to highlight some of the most exciting finds.

One of the most abundant types of ancient plates is the Roman military diploma. These plates, or the fragments of them, are the remnants of the Roman retirement certificates given to military men exiting the service, often granting citizenship or honorable mentions. There are dozens, even hundreds, of these plates dating back to the Roman time period. The most comprehensive text about these records details over 600 separate plates in various conditions. 24 Brigham Young University recently (in 2006) acquired a set of two of these plates that were in relatively good condition. These plates are made of bronze and date to A.D. 109. Though inscribed on both sides, it is notable that the plates were cast using the lost-wax casting process, so while the casting created the lettering on one side the other was engraved using hand tools.25

There are additionally several plates that are made of precious metals. The plates of Darius are a prime example. These plates, which consisted eventually of a set of 10 metal tablets in gold and silver, were found in Hamadan, Iran. Like Joseph Smith’s gold plates, at least 6 of these were found in stone boxes, and are believed to have been interred during the reign Darius at about B.C. 515. The plates however, “constitute the high point in a long tradition of concealed metallic documents, which persists from Sumerian to Alexandrian times.”26 Another set of plates, these made of gold, of silver and of copper, date back to the reign of Assyrian king Sargon II in the late 700’s B.C

Recently a group of 120 gold gilded plates came to light from the depths of a Chinese emperor’s tomb. These 6 separate sets of 20 “pages” that are hinged together are quite stirring because a significant portion of the Quran is written across them. These are potentially the best comparison to the plates Joseph Smith claimed to posses because they contain long pieces of an important religious text, but also because they are copper based with gold gilding (though the gold surface perhaps was not achieved in the same manner).

The hinging on the plates also forces one to question to idea of a three-ring compilation method. Though hinging probably would be the less simple method, it would allow for a more compact codex. The rings are not dimensioned in descriptions of the plates, which could be problematic given the snug fit the plates would have had in many of the boxes it was reported to have been stored in.

The gold Quran is also noteworthy for its writing, which is done by impressing the metal in the shape of the characters. This does not allow for recto-verso writing, unlike Orson Pratt and John Whitmer’s descriptions of the gold plates.27

Despite this plethora of ancient plates in the Old World, the situation in the Americas is less encouraging. In John Sorenson’s section on the metalworking of ancient Mesoamerica there is so little evidence of plates that he is obliged to grasp at unsubstantiated scraps of rumor from Jose Antonio Gay’s Historia de Oaxaca. 28 Paul Cheesman cannot even give a convincing argument that there was a writing system in the Pre-Columbian Americas, forced to resort to a potential communication system based on “strange marks… incised [on] lima beans”.29

However, there are some promising artifacts from the right land mass. Heather Lechtman describes in her article “A Tumbaga Object from the High Andes of Venezuela” a small thin semi-circular sheet of tumbaga discovered by Erika Wagner. The most notable fact about this curious little piece of golden tumbaga is the fact that it must have been cast. In examining the crystal structure of the grains, it is clearly evident that it must have been cut from a larger sheet of tumbaga cast to a final thickness of a couple of tenths of a millimeter. And despite its extreme thinness, it was still gilt using the depletion gilding technique described earlier. By carbon dating charcoal samples from site where this was found, the charming little piece of metal can be dated to somewhere around 1000 A.D. There are also several older artifacts made of hammered tumbaga, rather than cast sheets. However the evidence for sheets with writing on them is quite lacking. With all of these examples in view, I have to conclude that Mormon perhaps used a combination of Old World engraving and New World sheet metal processing.


I hope I have expressed, my conclusions from this research are slightly inconclusive. Rather than a definite yes or no, I think it is wisest to simply place the idea of golden plates somewhere on the spectrum of plausibility. Mormon would’ve encountered serious challenges in making the plates. He would have had to be somewhat ahead of his time technologically. He would need to have been extraordinarily well trained. But making the plates is not an option that is out of the question. The story of his plate making doesn’t seem to contain any major holes, rather it gently and continuously pushes the envelope of our belief.




1. Bidamon

2. Testimony of…

3. Smith

4. David

5. Harris

6. Henrichsen (see reference 1)

7. Henrichsen (References 5,6,7)

8. See Petersen’s descriptions of the etymology and Lechtman article on the significance of metals

9. Lechtman (Significance…) 28

10. Please note that I will not attempt to defend every anachronistic technological claim made in the Book of Mormon. I will also not try to explain the textual or non textual references to other plates besides those Joseph had. Both seem to me as secondary questions based upon the legitimacy of the golden plates. And lastly I will not deal with any questions regarding the data storage capacity of the plates, meaning the linguistic compactness of the characters, the font size and line spacing, and speculation on how many plates would’ve been required.

11. Mineral Map and Brandes 7-4

12. Petersen 23-29, 47-54

13. The process essentially boils down to the following equation: 2CuO + C  2Cu + CO2

14. This first step of mining and extracting poses a question that is relevant to the entire creation process. Were the Book of Mormon plate makers using Old World or New World technology? Nephi discusses teaching his apparently vast skills as a craftsman to his people, saying, “And I did teach my people to build buildings, and to work in all manner of wood, and of iron, and of copper, and of brass, and of steel, and of gold, and of silver, and of precious ores, which were in great abundance.”14. However, it seems possible that by the time Mormon is making his set of plates (which constitute the majority of the plates that Joseph Smith would’ve received), the technology of such an outpost of Israelite culture would’ve sufficiently mixed with that of the ancient locals such that they would be indistinguishable. Because of that, and because I don’t want my argument to rest entirely upon the feasibility of a transoceanic voyage 2600 years ago, I will attempt to provide a process that is based on the ancient American technologies.

15. Horz 396

16. Bergsoe (Gilding) 37

17. Horz 396, 410

18. Petersen 56

19. Lechtman (tumbaga object) 481. He further could’ve used the method she suggests of using a two-in-one crucible-plus-mold to melt the alloy directly into the mold.

20. Henrichsen (see references 37 & 40)

21. Henrichsen (see reference 32)

22. Henrichsen (see reference 31)

23. Petersen 63

24. See the 5 part works of Margaret Roxan and Paul Holder

25. Welch

26. Wright 49

27. Henrichsen (see references 37 & 40)

28. Sorenson 283, 391

29. Cheesman 88