De Re Metallica (Hoover English translation)

their clarity is like crystal to mud in comparison with those of his predecessors—and of most of his successors for over two hundred years. As an indication of his grasp of some of the wider aspects of geological phenomena, we reproduce, in Appendix A, a passage from De Ortu et Causis, which we believe to be the first adequate declaration of the part played by erosion in shaping mountains. But of all Agricola's theoretical views, those relating to the origin of ore deposits are of the greatest interest, for in these matters he had the greatest opportunities for observation and the most experience. We have reproduced and discussed his theory at considerable length on page 108, but we may repeat here that in his propositions—that ground waters circulate, that ore channels were created after the surrounding rocks, and that they were filled by deposition from circulating solutions—he established the foundations of our modern theory. In doing so, he took a step in advance greater than that of any single subsequent authority. In his contention that ore channels were created by the erosion of subterranean waters, he was wrong, except in special cases; it was not until two centuries later that a further advance was made by Van Oppel’s recognition of the role played by fissuring in these phenomena. Nor was it until about that same time that the filling of ore channels by deposition from solutions was generally accepted. While Werner, two hundred and fifty years after Agricola, is generally revered as the inspirer of the modern theory by those whose reading has not taken them any further back, we have no hesitation in asserting that, of the propositions of each author, Agricola's were much more nearly in accord with modern views. Moreover, the main result of the new ideas brought forward by Werner was to halt the march of progress for half a century, instead of speeding it forward as Agricola’s did.

In mineralogy, Agricola made the first attempt at a systematic treatment of the subject. His system could not have been otherwise than wrongly based, as he could scarcely foresee the atomic theory or our vast fund of chemical knowledge two or three centuries later. However, based as it is upon properties such as solubility and homogeneity, and upon external characteristics such as color and hardness, it represents a most creditable advance over Theophrastus, Dioscorides, and Albertus Magnus—his only predecessors. He was the first to assert that bismuth and antimony are true primary metals; to the approximately sixty mineral species described before his time, he added about twenty more, lamenting that scores remained unnamed.

As to Agricola's contribution to the sciences of mining and metallurgy, De Re Metallica speaks for itself. While he describes scores of methods and processes for the first time, no one would contend that they were his own personal discoveries or inventions. They represent the accumulation of generations of experience and knowledge; but through him, they received a detailed and intelligent exposition for the first time. Until Schlüter's work nearly two centuries later, it was not surpassed. There is no measure by which we may gauge the value of such a work to the men who followed in this profession over the centuries, nor the benefits enjoyed by humanity through them.