Roger Weller, geology instructor
The first view is a mineral
observed under normal light,
while the second is the same mineral viewed under ultraviolet light.
There are two minerals in this specimen.
The white mineral is celestite, which does not fluoresce,
while the pale brown mineral, fluorite, fluoresces.
Photos are copyright free for non-commercial educational uses.
Just credit photos to R.Weller/Cochise College.