I am trying to help a friend identify a number of coins he bought as part of an "ancients" collection. I have succeeded with most of the Roman except this one. Because it appears to be gold I feel it is worth the extra effort! Measures approx 14.5mm across and weighs 3.1g. My estimate to SG is about 19.6g/cc. I am stumped because I feel the lettering is in the Greek alphabet, and so possible Alexandrian mint? Thanks,
It is bronze. Bronze has a gold-ish appearance when it has been stripped of patina. Here's another example of the coin and it too has been aggressively cleaned at some point and is developing a new patina (or perhaps it had a patina applied). MYSIA, Pergamon 40-60 CE, time of Caligula to Nero Æ15, 3.2 gm, 12 h Obv: ΘЄON PΩMHN; bust of Roma with mural crown right. Rev: ΘЄON CYNKΛHTON; laureate bust of Senate right. Ref: RPC 2374; SNG Aul.1385
More precisely, it is orichalcum. Bronze is an alloy of copper and tin. Orichalcum is a mix of copper and zinc. It is common in provincial coins.
We should discuss this because Latin has no word for "zinc." The metals of the ancients were gold, silver, mercury, copper, iron, tin, and lead. I agree that we identify orichalcum that way in our time. I am not sure how they perceived it. (More in a different thread...) Thanks! Mike M.
Lydia, Hermocapleia I read ΠΗΛΙT.. on the left side of the obverse, which is on the right of the picture shown. Like here (Hermocapleia): https://rpc.ashmus.ox.ac.uk/coins/3/1878 ΕΡΜΟΚΑ on the right side, ΠΗΛΙΤΩΝ on the left side. The picture of chrsmat71 posted here on cointalk is better than the rpc example: I hope it is OK that I repost your picture here. Might be a die match.
The Romans did not need a word for zinc since they did not isolate the element as a metal. What they knew was that if you heated copper with a certain salt the copper became yellow, harder and better for many purposes. They had a word for that as gsimonel pointed out - orichalcum. Traditionally, numismatists use the word 'bronze' for any alloy that is substantially copper including pure copper, orichalcum, leaded bronze and what we today call pot metal with a lot of copper in it. There are times when there are two different alloys used with purpose and times where it seemed they used whatever fell in the pot. This is especially true when you consider how many old coins were melted to make new ones. Exactly where you draw the line is of greater interest to people who study metal than to people who collect coins.
Can I assume that the "certain salt" was zinc? Is zinc a salt? That does not seem correct to me, but I've been wrong multiple times just today. Or was there a particular salt the Romans had easy access to that was loaded with zinc? Sorry to be so inquisitive but my brain just won't let it go. Thanks and very best regards! David
I don't know the history but the chemistry is fairly obvious. Zinc is a metal but exists as many compounds in common rocks and minerals, including some containing copper. When refining copper from these minerals it is likely the zinc remained with the copper forming various levels of alloy. Trial and error would soon lead them to the ideal combinations to get the best Orichalcum depending on the proportions of different minerals used. Most likely compound would be Zinc Carbonate - found as Smithsonite in its pure form, but also occurring in Malachite, which is a Copper ore. Zinc would be difficult to get as a pure metal for the Romans as it oxidises rapidly in air, particularly at temperature. I remember as a teenager trying to melt down Zinc battery cases to get a Zinc ingot and ending up only with a white/yellow powder (Zinc Oxide). See also: https://en.wikipedia.org/wiki/Orichalcum
