Trivia - Total Number Of Roman Coins

Mintages of ancient coins are, for the most part, unknown. We can make educated guesses, but doing so is kind of like using the Drake Equation to calculate the number of extraterrestrial civilizations in the Galaxy: the number you get out at the end depends a great deal on the values of the unknowns at which you can only guess. In the case of ancient coin mintages, we know only slightly more than the SETI people do about their subject matter.

We have a reasonable guess as to the number of known different types of coins there are, due to extensive study of die matching. We can also work out approximately the maximum number of coins a die is likely to be able to produce before it becomes too worn out to use any more.

What we don't know is how many coin types there were that are unrecorded or have even disappeared completely from the historical record. The "best guess" we can do for this is similar to the method which environmentalists use to estimate the number of as-yet-undiscovered species in an ecosystem: take a random sample, and find out what proportion of never-before-seen specimens in that sample there are.

Nor can we know which designs were not struck to the maximum quantity the dies were capable of producing. For many coin types, the limiting factor in the number of coins issued was not die lifespan, but amount of raw metal available for coining - and this is something which we cannot possibly estimate, as detailed financial records of mint-cities have generally not survived.

Finally, of course, raw mintage figures alone don't tell us how many ancient coins are still around. Attrition affected ancient coins just as much as it does modern ones. I recall seeing that, for modern coins, the total number of surviving specimens of any one given type is typically down to about 2% of the original figure after about 100 years (the exact figure depending on many circulstances) and this would have been true in ancient times as well. Old coins have always been withdrawn and melted down to make new ones, coins exported to other countries melted down to make local coins, and coins irrevocably lost in other ways.

With ancient coins, who have not enjoyed the added protection of coin collectors souveniring the best specimens for most of their existence and for which many still remain buried in the ground, the present-day survival rate is more like 0.2%.

Thanks and speaking of survival rate, given the Romans had a penchant for burying their coins I would guess this would alter the per centages?