To be honest, I don’t quite know what causes it, but it would suggest something external to the tree’s systems. I could be mistaken, but this may also be the case with brown oak as well, and I believe that is caused by a fungus, so again, external source of discoloration.

I’m so curious about this. I have a piece that has that strange end-grain characteristic. What causes that? Is it an identifying feature of this type of wood or is it common to a bunch of species?

Hard to tell from the picture, but it looks like just regular ash to me. You may be better able to tell in person than I can from a picture thought. Just keep in mind that the olive figuring has some unusual characteristics that are independent of the wood’s grain. If you look at the endgrain photo here, you’ll see that the figure does not coincide with the wood’s growth rings, and sort of have a life of their own.

No, at least the smell is not the same. Though I have worked with some pieces of ash that were quite aromatic, but not the same odor as olive.

White Ash can be Olive Ash. I buy my boards from a local arborist. Sells what he cuts down. I picked up some Olive Ash from bim just last month

it’s a really nice bowl you made there but it is not olive ash. that is tiger oak which is just oak that was well on its way to becoming proper brown oak. a much scarcer wood to find.