Rear axle for Alexrims DC 4.5 Disc 26" MTB wheels w/ Formula hubs
If the hub has a smooth, straight-walled 12mm diameter hole through it, yes it's for a 12mm through axle. (A 'through axle' isn't really the axle of course, it's a fastener that goes through the hollow axle in the hub.)

If this is the case, there are through-axle to quick release adapters available that you can use. 

BTW, have you checked that the hub width is correct for your frame?

UPDATE: Nope not through-axle. Just missing axle and bearings.