The Golden Spider by Francis Lynde

At the summons for which they had been looking――and hadn't looked judiciously enough――the three Golden Spiders, kneeling beside the partly sorted pile of ore and broken stone, were taken at a tremendous disadvantage. Larry's rifle was the only one within reach, and this had been put down while he was handling the piece of rich ore that Dick had thrust at him.

The intruder, a heavily built man with a swarthy face, ragged black mustaches and a beard that looked as if it might be a month past its last shave, had apparently come well prepared to enforce the notice to quit. He carried a rifle in the crook of his arm, and there was a formidable-looking pistol sagging in its holster on his right hip.