In the barren plains country they would be called desert rats, but in the mountains they are called prospectors.
They set up their own camp half a mile down the creek, so that Kate and Marion seldom saw them.

They did their own cooking and divided their work to suit themselves, and they did not charge as much for their labor as Fred charged the claim-owners for the work, so Fred considered that he had done very well in hiring them.

He could turn his attention to his own claim and the claims of Marion and Kate, and let the professor peck away at a hole in the hillside where he vaguely hoped to find gold.

Why not?
People did, in these mountains.

Why, nuggets of gold had been picked up in the main street of Quincy, so they told him.