Boron, arsenic, and antimony, among other substances, are used as dopants when added to a pure semiconductor material to alter its electrical characteristics.
Artificially produced gemstones[?] (such as Ruby (gemstone)) usually contain a dopant to identify them as such.
... the gyroscope is best when the precession of the gyroscope is supported and amplified by wrist motion.
It takes a while until one finds the "rolling" point, but the gyro ...