De Natura Fossilium is Georgius Agricola’s Latin treatise on the nature of “fossils,” a term used in his period for substances dug from the earth. The English volume titled De Natura Fossilium (Textbook of Mineralogy), translated by Mark Chance Bandy and Jean A. Bandy, presents Agricola’s systematic survey of mineral substances: earths, salts, alums, vitriols, nitre, sulfur, bitumens, stones, marbles, gems, metals, and related materials. Its subject is mineralogy, not the study of organic fossils in the modern paleontological sense. The book is concerned with the composition, properties, classification, occurrence, and uses of earthy and mineral materials, together with the terminology used by miners and earlier writers.
The Latin treatise is arranged in ten books. Across them, Agricola moves from general questions about the nature and formation of mineral substances to the description of particular classes of materials. He retains a traditional framework in which minerals are understood in terms of earth and water, “juices” that congeal or harden in the earth, and the effects of heat, cold, and time. Yet the descriptive core of the work is comparative and observation-based. Agricola draws on classical authorities—especially Theophrastus, Pliny, and medical and natural-historical writers—but he also tests and supplements their statements against materials known from mines and workshops, especially in the mining regions of Central Europe.
A central achievement of the book is its attempt to classify mineral substances by observable physical properties rather than by medicinal or magical virtues alone. Agricola discusses colour, lustre, transparency, hardness, weight, taste, smell, fusibility, solubility, fracture, shape, and behaviour under fire. He uses such properties to group materials and to distinguish one substance from another. He also records localities and modes of occurrence, and he describes the occurrence of many ore minerals. This attention to physical character, local occurrence, and practical identification gives the work its importance in the history of mineralogy.
The treatise treats a wide range of materials. It discusses earthy substances such as clays and ochres; soluble salts and related materials such as salt, nitre, alum, and vitriol; sulfur and bitumens; stones and ornamental stones; gems; and metals and metallic substances, including gold, silver, copper, iron, lead, tin, mercury, and bismuth. Agricola is interested not only in identification but also in how substances are formed, where they are found, how they are extracted or prepared, and how they are used. The work therefore combines natural history, mineral description, and practical mining knowledge.
Another important feature is Agricola’s attention to nomenclature. He compares Latin names inherited from ancient authors with contemporary German and miners’ terms, and he tries to match ancient descriptions to the materials actually found in his own region. Where identification is uncertain, he reports alternatives and notes disagreements. This concern with names and synonyms is integral to the book’s project: it seeks to bring the confused vocabulary of older natural history into relation with the observable substances of the mine and the workshop.
Because De Natura Fossilium is a Renaissance treatise, it does not use modern chemical formulas, crystallography, or geological stratigraphy. Its classifications rest on sensory properties and practical tests, and its explanations of mineral origin are premodern. Its value lies in its comprehensive scope, its careful recording of physical characters and localities, and its attempt to impose order on a large body of mineral substances. The English translation makes available the full text of Agricola’s mineralogical survey, including its descriptions of mineral occurrences and its effort to systematize the mineral kingdom as it was understood in his time.
One of the book’s central conceptual moves is its use of fossilia in the older, broad sense of things dug from the earth. Its subject is not the remains of organisms but the whole range of subterranean materials—earths, stones, gems, salts, bitumens, metals, and related substances. Agricola treats these as belonging to one extended field of natural history, so that differences among them are questions of composition, mixture, purity, hardness, and degree of concretion rather than of separate natural kingdoms.
A key organizing idea is the category of succi, or juices: mineral moisture that thickens, coagulates, or hardens within the earth. This category links materials that later mineralogy would separate, such as salts, alum, vitriol, sulphur, and bitumen, and it allows Agricola to explain them as products of natural processes rather than as isolated curiosities. The book pairs description with causal explanation: it asks why a substance is hard, fusible, soluble, heavy, or metallic, and it interprets such differences through moisture, heat, cold, time, and mixture in the earth.
In treating metals, Agricola keeps the metal distinct from its ore, its gangue, and the associated substances in the vein. He describes the signs by which ores are recognized, the associations in which they occur, and the changes produced by fire. This integrates metallic description with practical mining and metallurgical knowledge, and it makes the work useful for identification and extraction as well as for natural-philosophical inquiry.
The book also has a critical, comparative dimension. Agricola juxtaposes ancient descriptions with contemporary materials and with miners’ vocabulary, and where a name cannot be securely matched to a substance he reports uncertainty and competing identifications. Naming thus becomes part of the empirical work: it is a way of fixing observations and communicating them, not merely a philological ornament. The result is a survey that combines property-based description, attention to locality and occurrence, and an attempt to bring the confused vocabulary of older natural history into relation with the materials actually handled in mines and workshops.
