Figure 3a: From the adit of the Silver Crater Mine. Note the proximity of the betafite (the uranium mineral) to the biotite where Po halos are found. Gentry claims there is no uranium source to feed the halo centres. Photo by J.R. Wakefield (1988)
Figure 3b. From the same location, notice the nice betafite crystals and their proximity to the biotite. Photo by J.R. Wakefield (1988).
Figure 3c: Same location, this shows the small inclusions of calcite that did not get replaced when the biotite grew in the solid calcite. Photo by J.R. Wakefield (1988)