A variety of quartz to which many medicinal values were attributed
in ancient times. It was believed to prevent fever and
dropsy, strengthen the brain, and promote eloquence. It was
said to prevent defluxions (discharge of catarrhal mucous),
nightmares, and epilepsy and was often used in the East as a
countercharm. Bishop Marbodeus mentioned 17 species of this
stone but noted that, like the emerald, it was mainly sought for
its magic properties. As late as 1609 it was still believed that jasper
worn about the neck would strengthen the stomach.