What hardness variance do we see on found mail? Is it generally iron, mild steel, or what?

Here's a brief article from Dr. Williams if you don't have access to his book.
http://www.themailresearchsociety.erikds.com/pdf/tmrs_pdf_6.pdf

Wrought iron is the most common material, with diamond/Vickers pyramid hardness around 80-85. As early as the 12th century, we start getting references to "steel" mail, though it is notable for it's rarity or cost. Some of the early steel is not very homogenous, and hardness can vary across the ring. By the 16th century there are samples of hardened medium-carbon steel being used in mail with dph/Vph in the 500-600 range. Williams' Specimen 9 from the 16th century having a Vph of 587kg.mm-2 , about 7 times harder than wrought iron mail of the Roman through early medieval period.

It seems to mainly have been low carbon, highly refined iron (probably because it was easier to pull through a draw plate) but a lot more of it needs to be analysed to come to more specific conclusions. Later examples are more likely to be harder.

Edit: ninjaed by Mart

I'd be interested to see how hardened mail would perform. If it's like plate then it would be about 50% stronger than the mild steel mail Williams tested for The Knight and the Blast Furnace.

Appreciate the info, and nod to the wealth of knowledge possessed by the members of this forum