This is a wood cutting bandsaw, so no way is it metal chips, etc. But I'll go at it tomorrow with something to expose metal, and see what it is. It could be a steel hoop that was heated to expand, and then cooled in place onto the cast iron wheel, then torch-welded or brazed in a few spots. Think 1920's tech. But either way, up-close inspection reveals the hoop is definitely a separate piece from the cast wheel, and I do believe the hoop is steel.
One more wrinkle, this chipped wheel is just a replacement wheel, which has a different hub configuration from the original upper wheel. So, if I use it, I still have some work to reconfigure and bush out the hub.
On the flip side, I also have the original, but a whole section has been broken out of it. I have those pieces, but had assumed skarfing them back in to make a repair was impractical:
View attachment 854272
Third option is just have a whole new wheel made. Could have replica of original cast by Cattail Foundry, and then turned and balanced by a local machine shop. If doing that, I'd just scarf the original back together and let the guys at the foundry build it up, to use the original as a mold for a new wheel.
Fourth option is to keep shopping for another wheel. But on a 100+ year old machine of a less common size, they don't come up very often, and more often than not they're worse than what I already have.