With Descriptions of 279 Gems and Stones

MINERALOGY. Leonardi, Camillo (1451-1550)

The mirror of stones: In which the nature, generation, properties, virtues and various species of more than 200 different jewels, precious and rare stones, are distinctly described. Also certain and insallible rules to know the good from the bad, how to prove their genuineness, and to distinguish the real from counterseits. Extracted from the works of Aristotle, Pliny, Isiodorus, Dionysius Alexandrinus, Albertus Magnus, &c. By Camillus Leonardus, M.D. a treatise of infinite use, not only to jewellers, lapidaries, and merchants who trade in them, but to the nobility and gentry, who purchase them either for curiosity, use, or ornament. Dedicated by the author to Csar Borgia. Now first translated into English.

London: printed for J. Freeman in Fleet street, 1750


Octavo: 17.2 x 11 cm. xiv, 15-119, 200-240p. Collation: A-K8. Complete.


Bound in contemporary calf, rebacked. Bookplate of R. E. W. Maddison (d. 1993), Librarian to the Royal Astronomical Society and author of "The Life of the Honourable Robert Boyle."

First English edition of Leonardi's " Speculum lapidum"(1502), "The first original work on stones, gems, and minerals conceived after more than two centuries of silence by the scientists, but certainly not of neglect by the wealthy ones. Leonardi’s work, composed of three books written sometime between 1480 and 1500, describes all the stones he could find reference to, mostly drawing information from Pliny, but also from many other sources, especially the Arab ones mediated by the late medieval authors. His first book details how and where gems are generated, how they develop their forms, colors, and properties, and even how natural stones can be distinguished from artificial ones. Leonardi’s second book presents an impressive list of 279 gem names and descriptions in alphabetical order, the longest list compiled during the Middle Ages and early Renaissance." (Mottana, Italian gemology during the Renaissance: A step toward modern mineralogy)

Leonardi classifies gems and stones according to their color, hardness, porosity, weight and transparency. The author, physician to Caesar Borgia, had gathered his materials from many of the older writers, but "he shows some indications of having come under the influence of the newer methods of study which were about to be advocated by Agricola and his followers, in that he treats of certain physical properties of minerals in that he treats of certain physical properties of minerals, such as "Perspicuity and Opacity, Hardness or Softness, Gravity and Lightness, Density and Porosity" and of the importance of these for the recognition of various stones." (Adams).

This English translation omits the section on gemstones, which the translator planned to publish later and separately. Such a separate work, however, never appeared. "In addition to summarizing the contents, the translator provides a lively and amusing account of the rarity of previous editions and the lengths to which one English nobleman went to obtain a copy on the Continent." (Sinkankas)

ISTC T146554; Thorndike, History of Magic, 1923-58: 6, 298-302; Sinkankas, Gemology Bibliography, 1993: no. 3896