2.2" Quartz Encrusted Galena and Fluorite Crystals - Rogerley Mine
Here is a nice 2.2" cluster of Rogerley fluorite crystals with a large galena crystal, collected from the famed Rogerley Mine in County Durham, England. Portions of the fluorite and galena are encrusted in druzy quartz crystals. This particular kind of fluorite is unique in that it will actually fluoresce a beautiful purple-blue color in just natural light alone! Under short and long wave UV, these crystals fluoresce a vibrant purple color.
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.
Fluorite 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.
Silicon Dioxide, also known as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.
Galena is a lead based mineral that is in fact the primary ore of lead, and has been used for its lead content for thousands of years. Galena typically displays a gray metallic luster and forms cubes or octahedral crystals. The chemical composition of galena is PbS.