The Billon and Potin Tetradrachms of Roman Egypt
Roman Egypt is a numismatically complex subject whose structure was inherited from Ptolemaic Egypt. Under the Ptolemies, Egypt had a coinage system deliberately structured so as not to be freely convertible to Greek or Roman monetary standards. Egypt had its own monetary system and its government profited from all currency conversions.
Without going into the fascinating complexities of Ptolemaic and Roman Egyptian bronze issues, it can be observed that Ptolemaic silver tetradrachm issues were eventually continued under the Roman Empire as debased silver or billon (less than 25% silver) tetradrachms. Their nominal silver content equated to that of a Roman denarius, which defined the exchange rate.
When the tribulations of the late third century impacted this coinage, billon was replaced by potin, an alloy dominated by copper and lead with a nominal but small silver content.
Potin tetradrachm issues from Alexandria, beginning with the reign of Claudius II (268-270) and extending until the end of Provincial issues in 305, were prolific and despite the fact that they lasted only 37 years, form a very fascinating subset of numismatic history.
The issues of Roman Egypt are collected here:
Attractive potin tetradrachms are featured which will interest collectors of this subject.