Wood. Not threaded but wheel and parts seem to work properly. Not sure, but wood may be oak. There are two very similar ones on eBay for $1000. Disregard screen shot from ebay uploaded in error. I don't know how to delete.
What a nice spinning wheel. It is a real piece of American history. These spinning wheels are highly collectable, especially if they are American. It is from around 1860. If you want to sell it, ebay or a local auction house would be a good place.