A desert mine, probably from before 1936. Ovehead imagery here http://terraserver.homeadvisor.msn.com/image.aspx?t=1&s=11&x=1094&y=9816&z=11&w=2 Based on my admittedly very meager understanding of minerals, I believe this may have been a copper mine. Note that this vein is the vein that the mine shaft follows. Here it is at the edge of the opening of the mine,and it can also be found at the rock face at the back of the mine.