It may be readily demonstrated with two hand-sized milky quartz crystals in a darkened room. Simply take the prism edge of one crystal and rub it back and forth on the prism face of the other crystal. You may simply rub two prism faces together, but you get more light using the former method. Catholuminescence Cathodeluminescence is a distinctive visible color that is emitted by bombarding a small piece of quartz with cathode rays. This must be done in a vacuum to best see the visible color.
Trace elements influence the cathodeluminescent color of the mineral.
Star of the C axis Asterism is the last property I will mention. Asterism is not present in all quartz specimens. To see this property exhibited the specimen is best cut into a sphere or at least a high domed cabochon. As the mineral cools, the dissolved material exsolves out of the quartz structure into discrete mineral particles. In the case of asteriated quartz, the dissolved material is thought to be very small amounts of TiO2.