An urban miner is usually somebody of the tweaker variety who scavenges old junk and whatnot for copper or other semi precious metals.
Tweaker:I'm going up to China Hat to collect a couple of hundred pounds of bullet casings for a ten bag. You in?
Other tweaker; Naw, I'm gonna dig me some copper out of a dead washer and dryer I seen in the neighbors yard the other night.
First Tweaker:We're legitimate urban miners!
Both tweakers clink their cans of Camo and 211 together.
A person who looks for cans,bottles or anything that they can sell for money.
There was a urban miner searching for cans on the side of the freeway. They can also be a Can Fisher