”On this place we saw coinage of copper and tin for first time”. The place is Byzantine Balkan and Odo of Deuil, a crusader from 2. Crusades, wrote so because in the western Europe they only had coinage of silver so the use of not precious metals as coinage surprised him. I am now maybe asking a dumb question: Did late Roman and Byzantine coinages use BOTH copper and tin always? Do we have examples where only copper was used? There are plenty of copper ore. Tin ore is rarely. So why use both when copper is enough to mint coins? Anyone who knows?
Copper is a very soft metal, and not really good for coins - they wear out too quickly. When ancient blacksmiths discovered the addition of a little tin to copper created an alloy that was much, much stronger, it was the dawn of the Bronze Age.
Most coinage is not made from "pure" metals, but alloys. Brass and bronze are the common ones for copper.
Hmmm? ... ummm, is the As perhaps a bit more copper, or did I miss a lecture and photo-copy some bad notes? either way => here is a sweet Nero As example ...
To be sure, some Roman issues were struck of pure copper - or as pure as they could get it, but that doesn't negate my point. Those coins are much softer, and much more difficult to find in higher grades as they wore easier. After a handful of 1st-century Imperial issues, the Romans abandoned pure copper for bronze. Orichalcum sounds very fancy, but it was merely a type of brass alloy that closely mimicked the color of gold.
