Photograph of four men in army uniforms, standing outside a building, preparing for inspection. Two brush their hair, another holds a mirror, and the last adjusts his cuffs.

Photograph of two soldiers in uniform, pretending to fight. The one on the left has his fists up, and the other holds one of them in his hand.

Photograph of a solider in uniform sitting on a rock. His hands are clasped in front of him, and the ground around him is made up of sand. A house and trees can be seen in the background.

From Introduction: "The results of concentration experiments with these ores made a more thorough and systematic investigation desirable. In consequence, the author subsequently collected samples in the district, and these became the basis of the experimental work described in this report. The results are published by the Bureau of Mines as a part of its efforts to increase efficiency in the utilization of mineral resources."