gems, jade, Fischer-Book

An encyclopedic treatise by Isidore of Seville on the structure and phenomena of the natural world, written in the early seventh century. De natura rerum discusses cosmology, astronomy, time, the calendar, the heavens, atmospheric phenomena, the earth, seas and other aspects of nature, drawing heavily on classical and late-antique authorities. Unlike Isidore’s Etymologiae, it is not a major lapidary or mineralogical source, and gemstones are not a principal subject. Its importance lies chiefly in the transmission of ancient natural philosophy into the medieval Latin scholarly tradition.