The last of the medieval lapidaries to be mentioned is that of Leonardus.
It is a significant fact that in all the lapidaries which appeared prior to the sixteenth century the minerals, when any definite system of classification was adopted, were arranged and listed in alphabetical order.
The number of species enumerated differs largely in different lapidaries. Marbodus mentions 60, Albertus Magnus 93, the Steinpreis Lapidary 117, Leonardus, who gives a longer list than any other writer, catalogues 279 separate names.
It may be of interest here, in order to present an adequate idea of the character and contents of these medieval lapidaries, all of which cover essentially the same ground although some of them do so more thoroughly than others, to select two, those of Marbodus and Leonardus, and describe them in some detail.
This Evax is also referred to by Pliny in the twenty-fifth book of his Natural History in the following words, "Evax a king of the Arabians, wrote a book as touching the virtues and operations of Simples, which he sent unto the Emperor Nero." Nothing further, however, is known of this person so frequently mentioned in the medieval lapidaries.
Many of the minerals are, however, as is the case in all the medieval lapidaries, merely names to the modern student, and cannot be recognized as designating any mineral now known to be a true mineral species.
In fact the Speculum of Leonardus, which was one of the most widely read lapidaries of the time, in its successive editions bridged over the transitional period between the old and the new mineralogy, since the first edition appeared in 1502, or forty-four years before the publication of Agricola's De Natura Fossilium, while the last or English edition coming from the press in 1750, brings us nearly to the time of Werner.
It will be noted that these medieval lapidaries, although they are the most important source from which information concerning the mineralogy of the Middle Ages is derived, really supply relatively little knowledge concerning the actual character of the minerals of which they treat.
The lapidaries are essentially handbooks of magic and medicine.
Other well-known lapidaries, all of which followed the same traditional treatment of the subject, appeared during the sixteenth and seventeenth centuries and may here be mentioned in the order of their succession.
Two other important lapidaries which were written under the influence of De Boodt appeared shortly after the publication of his work.