FLUORITE WITH QUARTZ

ABOUT THE SPECIMEN Small cluster of intergrown fluorite cubes showing strong zoning when backlit (as with the first photo). Along with more commonly seen purple crystals is one with a vivid, icy blue coloration.   VIDEO   MORE INFO The Yindu deposit is a silver-lead-zinc system in Hexigten Banner, sharing the same broadly Yanshanian-age skarn and hydrothermal setting common to several Inner Mongolian polymetallic deposits in the region - fluorite precipitated as a gangue phase during the waning hydrothermal stages in open vugs and fractures. Color ranges broadly from sea-blue and blue-green through saturated purple to rare magenta and red, with irradiation-induced lattice defects the most likely mechanism; the exceptionally complex phantom zoning - where abrupt shifts in color record distinct pulses of changing fluid chemistry - is the deposit's defining mineralogical feature and what distinguishes it from the more uniformly zoned Yaogangxian material. Crystals are predominantly cubic, sometimes modified by octahedral faces, and carry a notably higher color saturation than many competing Chinese localities at the cost of somewhat lower average transparency. Associates include quartz, muscovite, pyrrhotite, chalcopyrite, and calcite. The locality entered collector awareness around 2017 and has since produced a wide enough variety of color combinations and forms that no two pockets appear identical; supply has been consistent enough to keep prices accessible, though the finest phantom-zoned pieces on matrix have absorbed into collections steadily and are becoming harder to source at their original price points.