gems, Arabic mineralogy, early gemology, al-Biruni, al-Kindi, al-Tifaschi, early lapidaries

Ruska surveys the character and development of mineralogical knowledge in Arabic literature, emphasizing that medieval “mineralogy” embraced not only stones and ores but also technically produced substances, pearls, coral, and fossils, and differed fundamentally from modern mineralogy in its emphasis on readily observable physical properties, behavior in fire and acids, medicinal uses, magical powers, localities, varieties, and practical applications rather than crystallography. He traces this knowledge through Arabic pharmacological, cosmographical, natural-philosophical, and astrological writings, including Ibn Sīnā, Ibn al-Baiṭār, Qazwīnī, the Ikhwān al-Ṣafāʾ, and Arabic lapidaries attributed to Aristotle, Ḥunain ibn Isḥāq, and others. Particularly interesting are accounts assigning particular stones and metals to the planets and prescribing engraved images and astrological conditions for their use; Ruska connects this Arabic tradition with the Spanish Lapidario of Alfonso X and with later works of Albertus Magnus, Thomas of Cantimpré, and Konrad von Megenberg. He devotes substantial attention to al-Tīfāshī’s lapidary, which treats 25 precious and semiprecious stones according to their formation, localities, qualities, powers, and commercial value. As an example, Ruska discusses al-Tīfāshī’s account of emerald, including the medieval theory of its formation, the Egyptian emerald mines near the Red Sea, mining conditions, varieties and defects, medicinal and legendary properties, and valuation; the finest “beetle-green” emerald is stated to average four gold dinars per carat. Ruska closes by stressing the exceptional importance of al-Bīrūnī’s eleventh-century Kitāb al-jamāhir fī maʿrifat al-jawāhir, particularly for the history of gemstones and information concerning important stones of India, and expresses his intention to make the work accessible through an edition and translation.