Specimens like this are mostly sold as green and purple sodalite, but most are massive pieces. This piece contains part of a crystal that...

Yellow fluorescent aragonite due to organic impurities and possible lattice defects. Red fluorescent calcite showing Mn2+ and Ce3+-OH...

Rhombohedral calcite group, Beez, Namur, Belgium. It exhibits the typical yellow-green fluorescence and afterglow (PeL image). At shorter...