Reviewing this thread, and summing the species proposed so far, we have:
Pecan
Maple (incl. spalted maple)
Buckeye
Box Elder
Copper Beech (spalted)
Horse Chestnut
At the cellular level, nearly all of these woods can be readily distinguished from one another. We can continue to add species of what it might be, but to determine the actual correct name, a formal identification would be required looking at as many characters as possible (including facegrain pattern, bark, density, color, etc. if these characters are available), and using a wood identification key to systematically eliminate possibilities of what the wood might be, and arrive at an answer based on actual characters and not perceived "resemblances". Unfortunately from the close-ups we still can't see enough cellular detail to begin to go through a key, although I can see that the wood is probably diffuse porous.
Robert - do you have any pieces of this wood left that haven't been turned and finished? The best way to get an accurate identification will be to prepare a clean end-grain slice, and examine the cellular structure under magnification. If you could send a small piece of this wood to someone who knows how to identify wood using standard wood ID keys, this would produce better results than on-line ID attempts. You could try this yourself with some basic study of Bruce Hoadley's book,
"Identifying Wood" (See
HERE). If you don't know anyone who knows how to do this, I would be willing to run a sample through the keys and try to ID this wood for you. If you are interested in doing this, contact me directly, and I can provide some additional information for you.
Rob Wallace