Geology, Geography, cool things like that.
Fluorescent blue and green Fluorite
Cubic, gemmy crystals of fluorite on matrix from world famous locality - Rogerly Mine. Medium luster. Fluorite cubes are well coloured - green in artificial light with a strong blue daylight fluorescence, and an even stronger purple-white fluorescence under long wave UV light. This amazing fluorite crystals change colour in different lights - in natural light they are blue, in artificial light they are green.
Rogerley Mine, United Kingdom
unlike many cave networks that are formed by the erosion of water over limestone, the cueva de los verdes (or “green caves”) in the canary islands were formed three to five thousand years ago when surface lava cooled and hardened quickly while streaming lava continued to flow underneath the petrified basaltic layer. the caves were formed over a fifty kilometre squared area of more than one hundred volcanoes, the last of which erupted almost two hundred years ago. the lava tunnels can stretch for several kilometers, with some parts dropping well below sea level and reaching temperatures of up to six hundred degrees. photos by edwin jones (more cave photos)