Figure 2. Surface geology of the Fission Mine site. The mine is located just to the east of Wilberforce. The calcite vein-dikes are most likely of a hydrothermal origin. The biotite, and other minerals that occur as large crystals, were formed by growth in the solid calcite vein-dikes matrix by metamorphic processes. (After Bright, Map P.2597,1983, reproduced with permission.)