I couldn't work out the finish.
I don't think it's corroso, it does look more as if something was applied?
I've got a little signed posy vase with something that looks very similar, almost like sand. It produces a shiney iridesence in-between the dull bits. It's very boring and beige, apart from the strange surface, what appears to be a proper signature, a finished (again odd, possibly heat finished) pontil scar and date. I always meant to post it here to find out about the very strange surface texture. It feels like the fine side of an emery board!
Unfortunately, I'm unable to deal with pics just now. The pc died. I can't work the new one and I've lost my basic version of paint shop pro. I haven't got any files, documents, folders or tinkerbells or whatever things are called now, on this.
What exactly, is scavo, John? I don't think I know. I know the word, but not what it means.