Dual Phosphorescence: this stunning “Mexican onyx” bowl is carved out of natural rock that contains phosphorescent calcite that glows in the dark after exposure to ultraviolet light. If exposed to longwave (lower energy) UV-A it glows green, but if exposed to shortwave (higher energy) UV-C it glows a ghostly blue. Phosphorescence is a quantum mechanical phenomenon where high energy UV photons are absorbed by electrons which are then boosted to higher energy levels. The glow comes from these elec