This provincial coin is rather large (30 mm) and has some craters on its surface (filled in with dirt) that may have existed on the flan prior to striking. While I'm no expert on such things, @dougsmit has discussed these, both here and at his page. What do you guys think? Flan casting voids or post-mint corrosion? Feel free to post your coins with flan casting voids or anything you feel is relevant. A couple of photos, taken with different lighting conditions: Julia Domna, AD 193-217. Roman provincial Æ 29.3 mm, 13.67 g, 6 h. Ionia, Ephesus, AD 193-217. Obv: CЄBACTH IOY ΔOMNA, bare-headed and draped bust, right. Rev: ЄΦЄϹΙΩΝ TPIC NЄΩKOPΩN, carpentum drawn right by two mules. Refs: SNG Copenhagen 417; BMC 267 var. (obv legend).
They look like corrosion pits to me but I can't say I've seen many flan casting voids for comparison. There are oodles of pits on your coin, from tiny to large, so it looks like those pits are just varying degrees of corrosion. Can you find any definite examples of coins with casting pits where the pits are so numerous and varied in size but regular in shape?
I believe yours is corrosion as so ably explained above. My AE30 of Ephesos is a bit later style. I do not claim to be expert in his or anything but when I think of casting voids, I think of fewer, larger and more irregular faults.
I see no casting voids. The Gordian has centration dimples. Macrinus has corrosion. I would not expect the color difference on the Macrinus from a void there before striking.