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

Andrea Cesalpino’s De metallicis libri tres is a late sixteenth-century treatise on minerals, metals, stones, and related substances, organized into three books. Cesalpino attempts a systematic classification of mineral bodies according to their observable properties and modes of formation, discussing metals, metallic minerals, earths, salts, stones, and precious stones within an Aristotelian framework. He considers such characteristics as color, transparency, hardness, density, cleavage, and response to heat, together with the geological environments in which mineral substances occur. Precious and ornamental stones receive significant attention, including diamond, ruby, sapphire, emerald, topaz, garnet, amethyst, opal, and others. The work is an important early contribution to systematic mineralogy, notable for its effort to classify minerals through physical characteristics and natural relationships rather than solely through their medicinal or magical properties.