Here is a nice 1.42" Rogerley fluorite crystal from the famed Rogerley Mine in County Durham, England. This particular kind of fluorite is unique in that it will actually fluoresce a beautiful purple-blue color in just natural light alone!
is a halide mineral comprised of calcium and fluorine, CaF2. The word fluorite is from the Latin fluo-, which means to flow. In 1852 fluorite gave its name to the phenomenon known as fluorescence, or the property of fluorite to glow a different color depending upon the bandwidth of the ultraviolet light it is exposed to. Fluorite occurs commonly in cubic, octahedral and dodecahedral crystals
in many different colors. These colors range from colorless and completely transparent to yellow, green, blue, purple, pink or black. Purples and greens tend to be the most common colors seen.
The Rogerley Mine is located in the historic Weardale mining District of Northern England. First discovered in the early 1970's, the Rogerley Mine is the only mine in all of Britain to be worked on a commercial scale in the name of collecting crystallized mineral specimens. Since the summer of 1999, UK Mining Ventures has operated the Rogerley Mine on a seasonal basis, producing many fine, well crystallized specimens of green fluorite
. The Rogerley is considered some of the finest fluorites in the world and much of it has incredible fluorescence.