Fluorite.

Fluorite.

Fluorite is calcium fluoride, CaF2  It may be called fluorspar, and is a halide mineral. In a pure form Fluorite is colourless and transparent, however it is an allochromatic mineral and is very variable in colour because of the inclusion of trace elements. This specimen is light purple in colour and is a slab of well formed and intergrown cubic crystals on a limestone matrix. The location is loosely given as Egremont  in Cumbria.