On the widely used MOHS scale of hardness, diamonds are at a 10 scale, and crystal is at a 7 scale. One of the main sources of Rainshow'r crystal is Arkansas. It possessed a strange kind of electrical property. The piezio electric effect was first observed in the laboratory. Several minerals, including tourmaline and sphalerite, also exhibit this effect.
Electricity is electrons in motion.
A small electric pulse can be generated from some crystals whose atomic arrangement allows the electrons to move in certain directions, and quartz is one of the minerals that have this property. The flow of electrons is caused by a change in the shape of the crystal, which can be induced mechanically or thermally. Luminescence is light or a glow. Triboluminescence is light that is produced by pressure, friction, or mechanical shock. It may be readily demonstrated with two hand-size milky quartz crystals in a darkened room.