I had a pothole put a scratch & nick in the brushed outer edge of one of my black star bullet rims. I'm going to attempt to wet sand, steel wool & polish it out, but wanted to see if anyone knows exactly:

a) what metal these rims are (I'm assuming aluminum)

and

b) is there any kind of synthetic (clear coat, etc.) finish on the outer brushed metal edge, or is it just unfinished bare metal? I'm just concerned with the outer silver edge - not the painted black inner areas.

Thanks in advance