Thanks for the suggestion, that is the best site I've seen on the topic so far. I'm more convinced that this is white oak; however, since the local pro seemed convinced that it's red, I'd love to get some validation.
The comments at wood-database.com said to try vinegar and steel wool. I tried that overnight, and it did turn dark brown, however other sites seem to indicate this would be the case whether it's red or white-- I'm not sure if it's really a valid substitute for sodium nitrite. The rays also seem a little long for red.