The German naturalist Abraham Gottlob Werner (1749-1817) wrote the first modern textbook of descriptive mineralogy and was the major proponent of the Neptunian theory of the earth.

Abraham Werner was born on Sept. 25, 1749, at Wehrau in Upper Lusatia (Prussian Silesia). His ancestors had been employed in the mining industry for several hundred years, and his father was the overseer of a foundry in Wehrau. When he was 10 years old, Werner went to school at Bunzlau, Silesia, but five years later he returned home to become his father's assistant. However, his interest in mineralogy became so strong that he abandoned this practical career and in 1769 entered the Mining Academy of Freiberg. After two years there he matriculated in 1771 at the University of Leipzig.

Investigations in Mineralogy

During his stay at Leipzig as a student, Werner became acutely aware of the unsatisfactory character of the numerous systems used at the time to describe and classify minerals. Two conflicting approaches, based respectively on the chemical composition and on the physical characters of minerals, had created a confused association of unrelated observations, imprecise definitions, and impractical tabular arrangements. In the amazingly short time of a year, Werner wrote and then published Vonden äusserlichen Kennzeichen der Fossilien (1774; On the External Characters of Fossils, or of Minerals), the first modern textbook of descriptive mineralogy. Although Werner recognized that a true and final classification of minerals should be based on their chemical composition, he emphasized that it should be preceded by a method which would allow a precise identification of the various minerals by means of their external characters and physical properties.

Werner's description of the external characters of minerals, which occupies the major part of his book, remains an outstanding illustration of his unusual gift of observation and his knowledge of minerals. However, the quality of his work on mineralogy decreases abruptly with the discussion of the crystalline forms, for he was a practical or applied mineralogist to whom the mathematical aspect of mineralogy was superfluous. He never realized the basic importance of crystallography, which he thought was applied mathematics rather than a branch of mineralogy.

Geognosy and Neptunism

Upon publication of his book on minerals, Werner left Leipzig and returned to his home in Wehrau, where he became involved in the preparation of field trips to collect minerals and visit mines. However, the Mining Academy of Freiberg, strongly impressed by his performance, appointed him in 1775 inspector and teacher of mining and mineralogy. His dogmatic but stimulating teaching filled his students with enthusiasm, and they returned to their respective countries zealously spreading Werner's geological concepts. Therefore, a full account of his ideas is obtainable only through their writings and particularly those of his foremost follower, Robert Jameson.

Werner's concept of the earth's crust may be visualized as an extension of his great desire for rigid classification. He had only contempt for the speculative naturalists who were concerned with theories about the origin of the earth, and therefore he called his subject "geognosy," or "earth knowledge," which he defined as the science concerned with the arrangement of minerals in the various layers, and with the relationship of such layers, in order to reach an understanding of the constitution of the earth. He emphatically stressed the precision of his observations but did not hesitate to make sweeping generalizations about the whole earth from his very limited experience in Saxony. He gradually changed his hypotheses into so-called "facts" by the simple process of repeating them many times with unshakable confidence. Therefore, Werner's system, which pretended to avoid speculation, actually became the most speculative and erroneous attempt at explaining the origin of the earth.

Werner subdivided the earth's crust into a series of superposed and distinct "formations." He believed that these formations could be recognized all over the world and would therefore provide the key to the understanding of the geology of any country. He adopted the old idea that the earth originally consisted of a solid core completely surrounded by a universal ocean, which was at least as deep as the highest mountains and contained great quantities of mineral matter. Since the sea played a fundamental role in this system, the name of Neptunism was given to Werner's school. In this universal body of water, chemical precipitation took place, generating and depositing all forms of rocks in a constant succession.

Because Werner did not believe that the earth had any kind of internal fire or other deep-seated source of energy, he was forced to consider volcanic rocks as recent and accidental products, which he explained by means of the old concept of the combustion of underground coal beds. A further strange characteristic of Werner's was his denial of the disturbances of the earth's crust, such as folding or tilting, as proofs of the internal energy of the earth. Beds were supposed to have been deposited essentially in a horizontal position, and those dipping more than 30° were considered as having been "locally disturbed" by processes which were not elaborated upon. This refutation of mountain-building processes as an expression of internal energy was naturally coupled with Werner's equally dogmatic refutation of the occurrence of past volcanic activity.

Origin of Ore Deposits

Werner's ideas on the origin of ore deposits were corollaries of his general theory on geognosy. He stated that mineral veins were due to the filling by precipitates of fissures developed on the bottom of the universal ocean. The fissures were formed either by contraction or by the effects of earthquake movements. Consistent with his negation of the earth's internal fire, he refuted the idea that veins could have been filled by the products deposited by solutions or vapors originating from within the earth. Despite his ever present dogmatism, Werner did, however, demonstrate the value of a geometrical classification of veins, and he also gave excellent descriptions of their internal structures.

In bad health, Werner retired to Dresden, where he died, a bachelor, on June 30, 1817. His death was felt by most of the profession as a relief from a unique example of scientific despotism during which a man of genius tried unsuccessfully, for his entire life, to mold nature into an inflexible framework.

Further Reading

• Biographical accounts of Werner are in Sir Archibald Geikie, The Founders of Geology (1897; new ed. 1962); Karl A. von Zittel, History of Geology and Palaeontology (1901); and Frank D. Adams, The Birth and Development of the Geological Sciences (1938; new ed. 1954).