When Is A Fouree Not A Fouree In History?

The official denarii of Severus Alexander are minted from an alloy containing less than 50% silver. Hoard coins often develop deposits (copper salts?) on their surface from long contact with other coins. As a chemist, you probably understand this process better than I. A fourree, on the other hand, will corrode from the inside out. Counterfeits of the period are sometimes fourrees and sometimes base alloy casts (so-called 'limes denarii'). It can be difficult to distinguish a genuine coin from a fourree or from a base metal cast. This was true in antiquity just as it is today, to the delight of the counterfeiters. Fourrees are usually unmasked only when the corroding copper core blisters through the silver plate. At a glance, I am not certain whether the linked coins are genuine denarii with surface deposits or fourrees but I lean toward the former. The German term for fourree is "subaerat" and I don't see it used in the Rauch listings.

As for the camera, I have to admit, a great many years ago I just turned it to the little flower (so not the mountain) icon which I assumed gave me the best closeup shots. And I never touched it since. So the fact I am speaking in terms of little camera icons vs depth of field or f-stop means I probably should explore learning about how to photograph these coins better!