“Owsley [Augustus Owsley Stanley III] was obsessed with making his product as pure as possible—even purer than Sandoz; which described LSD in its scientific reports as a yellowish crystalline substance. As he mastered his illicit craft, Owsley found a way to refine the crystal so that it appeared blue-white under a fluorescent lamp; moreover, if the crystals were shaken, they emitted flashes of light, which meant that LSD in its pure form was piezoluminescent—a property shared by a very small number of compounds.”

—Martin A. Lee & Bruce Shlain, Acid Dreams: The Complete Social History of LSD, 1985.