Brass in the Desert — Richard S. Wheeler

Gladstone Brass found out how to make his livelihood during the thirty years he prospected the arid wastes of the Nevada desert. He pried ore out of the few little deposits he discovered, then went town which he hated only long enough to trade his bits or gold for the supplies he needed. Otherwise he was devoted to keeping these arid, secret wastes all to himself, and that meant driving out rivals, invaders, interlopers, and adventurers. His only friend and companion was T a Mar a, a burro he d caught in a desert ca on after his mule died from a snake bite."