gems, jade, Fischer-Book, early gemology, early mineralogy, early lapidary

An astrological and medico-alchemical treatise examining the supposed correspondences between the seven classical planets, the seven metals, and seven selected precious stones. Petrus discusses the “sympathies” linking celestial bodies with terrestrial substances and the influences these relationships were believed to exert upon their properties and medicinal or occult virtues. Of particular gemological interest is its treatment of gemstones within the early seventeenth-century tradition of planetary lapidaries, in which particular stones were associated with planets and credited with therapeutic, protective, or talismanic powers.