Experiments of an Alchemist (Kind of)

So I decided to play with some things that I haven't, and many people haven't, played with before: Alloys. There are many common alloys out there, but I came across one that peaked my interest. As many people know, I am not only a jeweler, but I am also an Anthropologist working on my BA in Anthropology with a focus on Cultural Anthropology. In some research that I was doing for my class on Mesoamerican Archaeology, I came across an alloy called Tumbaga. Tumbaga does not have many set standards for it, but is an interesting alloy because it essentially fire scales with gold coming to the surface. In fact, the gold is so strong in the alloy that the Spaniards confused it for solid gold upon its discovery in Central America.

In some journals written by early explorers, I came across the magic numbers of 5:15:80. That is, 5% gold, 15% silver, 80% copper. So I decided to figure this out for myself.

Here is an image of the math that I sat down and figured out to make the Tumbaga using scrap gold and sterling silver into the mix. This math accounts for the varying qualities of gold, as well as the dillusion of gold using silver and copper.



So those of you who don't care so much about this topic, I recommend that you turn away now. Because this will get long and drawn-out. But feel free to stick around as I explain why I used the math that I did.

First and foremost, I weighed out my gold in grains.

18k:10grn
14k:70grn
10k:8grn

From there, i figured out the perecentage of gold in each part of alloy. I did this by using the standard of 18/24, 14/25, and 10/24. This means that 18k is 75% gold, 14k is 58% gold, and 10k is 41% gold. These alloys are cut using silver and copper, meaning that in 18k, 12.5% is copper and 12.5% is silver. This division of remaining percentages was also used on the other alloys to figure out those contents.

So then I figured out just how much of each metal I actually had.

.75 x 10 = 7.5grn gold (1.25grn copper, 1.25grn silver)
.58 x 70 = 40.6grn gold (14.7grn copper, 14.7grn silver)
.41 x 8 = 3.3grn gold (2.333grn copper, 2.333grn silver)

7.5 + 40.6 + 3.3 = 51.4grn gold

The total amount of gold that I had was 51.4grn, meaning that 5% of the total alloy was 51.4grn. So to figure out the necissary amounts of the other metals, I used 5% (using a root 20, essentially, which is ironically the root of Maya calculations), to figure it all out.

51.4 x 1 = 51.4grn gold
51.4 x 3 = 154.2grn silver
51.4 x 16 = 822.4grn copper

Now, that's how much metal is needed. However, because of the varying qualities of gold, there is already a base amount of copper and silver. So add those base amounts up.

1.25 + 14.7 + 2.3 = 18.25grn silver, 18.25grn copper

Then subtract those base amounts from the total metal required.

154.2 - 18.25 = 136grn silver
822.4 - 18.25 = 804grn copper

So the total of metals necissary is:

51.4grn gold
136grn silver
804grn copper

Add those up to find out the total amount of alloy available.

991grn of Tumbaga.
991/24 = 41dwt 7grn = 2ozt 1dwt 7grn

The other major issue that I came across was the issue of specific gravity. There is no standard for the specific gravity of Tumbaga. So I worked for hours on trying to figure this number out. Here's how I did it. Now, I don't know for sure that this will work. But I will find out.

Specific gravities:

Gold: 19.3
Silver: 10.4
Copper: 8.9

I took these numbers, and applied them to the alloy in relative proportion of the metals. I did this again by using a base root of 20 (based off of the 5% gold).

19.3 x 1 = 19.3
10.4 x 3 = 31.2
8.9 x 16 = 142.4

Add them up
19.3 + 31.2 + 142.4 = 192.9

Divide that by the root of 20
192.9 / 20 = 9.65

It appears that 9.65 is the specific gravity of Tumbaga, if this math is even remotely applicable. I guess we'll find out!




See you space cowboy...