Reference the Sterling Mine GANJ_Calender_08.
Photo: Calcite (red) and willemite (green) fluorescing under ultraviolet light in wall rock along the Sterling Hill mine tour.
Two small faults cutting almost vertically through the layers are unhealed and must have moved in the time since the rock cooled from a plastic state to a brittle state.
The black square (top, center) is a steel bolt holding the wall of the tunnel in place. The miners would pick at the ceiling or wall to test if it needed a bolt
The small circles are drill holes.