Rio Tinto was exhausted, or at least exhausted of what could be reached using methods of the time. The output of those mines tapered off around 200AD which coincides (not really a coincidence) with the reign of Severus and the beginning of economic troubles. You’re correct that they didn’t exhaust Dacian mines but they did lose access to them, also not coincidentally a few years before our favourite cabbage-farmer took power and did what he could to right the economy.
Rio Tinto was exhausted, or at least exhausted of what could be reached using methods of the time. The output of those mines tapered off around 200AD which coincides (not really a coincidence) with the reign of Severus and the beginning of economic troubles. You’re correct that they didn’t exhaust Dacian mines but they did lose access to them, also not coincidentally a few years before our favourite cabbage-farmer took power and did what he could to right the economy.