Article reprinted with permission and originally appeared in the March Issue of the NYMC Bulletin - http://www.newyorkmineralogicalclub.org/
“It’s Elemental” is a series of columns by Bill Shelton written this in year in recognition of the United Nations’ International Year of the Periodic Table of Chemical Elements.
There are only four metals that are usually considered when we discuss coins, especially before 1964 when the USA stopped making coins for circulation that contained much metal value. The same four metals also play a role in the mineral collector’s world because they provide mineral specimens for us to enjoy. On the standard periodic table, we find column 1B contains copper, silver and gold. Together, they are the three most common metals present in coins since the first coins were actually used in commerce.
Platinum actually does not fall in the same column but is the neighbor to gold and has seen limited use in the manufacture of coins. On one occasion, Russia made over 1.5million coins during the 1820’s and that may be the only case where we find much use until the recent interest in bullion coins has created a market filled by several different nations. None of these new issues were ever intended for circulation or general use. I am surprised to see a report that Egyptian artifacts made from platinum were found that date back to the 7th century BC. Also, Colombian remains from 2000 years ago are claimed to be made of platinum.
Regarding coins, I am using the term to refer to oval to round, flattened discs of metal and do not include other objects that may be used for trade, etc. in the distant past. Since we can rule out platinum here as well, the three remaining metals are the primary components of the coins we will discuss. A trip on the internet will easily take you to coins for sale that are in fact quite old. I tried this out and found a couple nice examples. A Roman bronze coin from 395 – 408 BC and a Macedon bronze from 336 – 323 BC serve as two among many. There are older ones that you may find as well as hundreds of items offered for sale.
The oldest coins might be from the 5th or 6th century and may be labeled as Lydian. For a mineral collector it gets interesting here because they are supposed to be made from electrum, a natural alloy of gold and silver. Many of us have seen specimens labeled this way for sale at mineral shows. A lot of other ancient coins were made from bronze, an alloy of copper with some tin. We can find stories about even older copper beads that are perhaps 10,000 years old. The coins are more likely to be from the year 700 BC or less.
Mineral collectors are aware of certain elements on the periodic table that are often included under the heading of native elements. It is routine to attend a mineral show or view an internet site and find all of the four metals mentioned above as natural specimens. We might see gold nuggets from Australia, silver wires from Mexico, copper crystals from Michigan or platinum nuggets from Russia. All of these seem to me to be readily available, despite the fact that they can be costly.
Ever more common are certain compounds, especially those that contain copper. The most common member of this group of four, copper supplies hundreds of examples at any mineral show. Here we can find ever-popular species such as azurite, cuprite and malachite. I would not believe you can’t find chalcopyrite; we often see little inexpensive samples labeled as bornite when they are really treated pieces of chalcopyrite with a paper-thin skin of bornite. Besides being far from natural, they are almost entirely made up of chalcopyrite. Trya destructive test and chip the sample to see whether the inside is anything like the colorful skin on the surface.
Searching for silver minerals will prove to be a little more difficult since they are far less available but you can expect to find pyrargyrite, proustite, stephanite and acanthite. They are the most likely ones to be found for sale. Even native silver appears to be a bit elusive compared to gold or copper. You can find dealers thatsell almost exclusively gold or copper but I never heard of a silver dealer in the mineral context.
Platinum is rare in many ways – compared to the others here, I believe it is the rarest of the lot. So, even native platinum will not be ever-present in a search. Also, the next most likely example, the compound sperrylite will also be less common as a choice at a sale event. Some sources will describe all of the platinum minerals as rare and it is true, especially by comparison. While there are other choices, many collectors will not see examples they are eager to add to a collection.
Gold is reported from 24,350 localities and can be found in about 30mineral species. The record for the most different species belongs to the Kochbulak mine in Tajikistan with 11 species. Added to the previous comments, some collectors also like auricupride, nagyagite or petzite but we have so few choices! Most widely present in collections as native gold.
Silver is reported from 4,757 localities and can be found in about 140 mineral species. The record for the most different species belongs to the Lengenbach quarry in Switzerland with 24 species. Added to the previous comments, some collectors also like andorite, boleite, eugenite, miersite and polybasite amongst over 100 others. Most widely present in collections as argentite or native silver.
Copper is reported from 3,152 localities and can be found in about 560 mineral species. The record for the most different species belongs to the Clara mine in Germany with 101 species. Added to the previous comments, some collectors like ajoite, dioptase, kinoite, libethenite, spangolite and turquoise amongst over 500 other. Most widely present in collections as malachite and native copper.
Platinum is reported from 424 localities and can be found in about 25 mineral species. The record for the most different species belongs to the Driekop mine in South Africa with 12 species. Added to the previous comments, some collectors like cooperate, isoferroplatinum or niggliite but we have so few choices! Most widely present in collections as native platinum.