June/July 2006

Economic Geology

A recap of economic geology in the CEMB (Part 11)

By R. J. Cathro

Central square of Joachimsthal and Saint Joachim’s church. To the left of the church is the headframe of the Svornost mine, which operated from 1516 to the 1960s, producing silver and uranium. The mine is currently used as a source of radon-containing water for the Joachimsthal spa | Photograph provided by Ivan Prachar, Czech Geological Survey

"Rather than the broader subjects of mining or geology, this series is focused more narrowly on economic geology, a name that wasn’t applied to the branch of the science previously called mining geology until early in the 20th century. Economic geology has been variously defined as the:

  1. application of geology to the practical problems of the industries and the arts … including the study of deposits of useful minerals (Lindgren, 1913);
  2. 2) application of the principles of the geosciences to the study of the origins, occurrence, and utilization of mineral deposits of economic importance (Champlin, 1998);
  3. 3) scientific investigation of mineral deposits and mineral resources, and the application thereof to exploration, mineral resource appraisal, mining, and mineral extraction" (by-laws of the Society of Economic Geologists; SEG, 2006)

According to Adams (1938, p. 277), the first scientist to develop a theory on the origin of metals may have been Aristotle (384-322 BC), who believed that the metals found in the earth’s crust have a celestial origin. It is possible that others theorized about the subject as mining and metallurgy were developing in Asia Minor, South America, and Asia but no written records have been preserved. The Romans were accomplished prospectors and miners; however, the origin of metals appears to be a question they ignored. Interest in the subject was apparently not renewed until the 15th century, when the alchemists postulated that individual planets were the heavenly bodies that produced the seven known metals. Thus, the sun produced gold, the moon produced silver, Mercury was responsible for mercury, copper came from Venus, iron from Mars, tin from Jupiter, and lead from Saturn.

Much of the initial focus of this series has been on the Central European Mineral Belt (CEMB) and this seems like a good time for a recap. Miners there stimulated interest in the application of science to the questions of how and why mineral deposits are formed. After Georgius Agricola arrived there in 1527, as a physician, he soon realized how adept the medieval prospectors and miners had become at discovering mineralization by panning creeks and recognizing favourable gossans, alteration minerals, and host rocks. He began to document the mining and metallurgical practices in the region, becoming the first person to use observation, rather than logic, in an attempt to understand the origin of metals. In the words of Hoover and Hoover (1912), he was “the first to found any of the natural sciences upon research and observation, as opposed to previous fruitless speculation.” Born as Georg Bauer at Glauchau (Saxony) in 1494, he is one of the most outstanding figures in the history of the geological sciences. The German novelist/scientist/philosopher Johann Wolfgang von Goethe compared him to Francis Bacon.

With the help of his friend, the Dutch-born theologian and classical scholar Desiderius Erasmus, Agricola published three landmark books at the Froben Press in Basle, using the newly invented printing press. They included De Ortu et Causis Subterraneorum (The Origin and Causes of the Subterranean Earth) and De Natura Fossilium (Textbook of Mineralogy), in 1546. The third, De Re Metallica (On the Subject of Metals), is the best known because of its translation into English by Hoover and Hoover (1912). It is a treatise on the arts of mining and smelting that contains only incidental references to geology and mineralogy, but is most noteworthy to geologists for its wonderful collection of 292 woodcuts that illustrated contemporary prospecting, mining, and metallurgical methods. Agricola’s insistence on the need to illustrate everything that he had seen delayed publication until four months after his death in 1556.

These woodcuts, which are some of the most beautiful and historic illustrations produced in the medieval period, were reprinted countless times and proved to be of immeasurable help to miners everywhere, even if they couldn’t read the German or Latin text. Basilius Wefring (also spelled Blasius, Weffring, and Weffringer) drew the images for the woodcuts in Joachimsthal prior to 1553 (Long, 2006; Hoover and Hoover, 1912, p. xvi). According to Long, the drawings were taken to Basle, where several carvers turned them into woodcuts. Two of the carvers, Hans Rudolf Manuel Deutsch and Zacharias Specklin, signed their work.

The CEMB mineralization occurred mainly as placer deposits as well as veins, which were simple structures that were easy to recognize as cracks in the crust. The miners had also exploited irregular tin alteration zones (greisen deposits) and complex sulphide bodies such as Rammelsberg (a sedex-type deposit). In addition to the seven previously known metals—gold, silver, mercury, copper, iron, tin, and lead—they soon encountered and learned how to recover or avoid at least twelve more. In alphabetical order, they are: antimony, arsenic, bismuth, cadmium, cobalt, germanium, indium, molybdenum, nickel, tungsten, uranium, and zinc, plus pyrite, barite, fluorite, and lithium. Lode mining had commenced as early as the eighth century in the CEMB (see previous parts of this series for more details): Banská Stiavnica [Schemnitz] (745), Pr?íbram (843), Rammelsberg (938), Freiberg (1168), Clausthal-Zellerfeld (1180), Ehrenfriedersdorf (12th century), Iglau (1249), Kutna Hora (1270s), Horni Krupko (1297), Sauberg (13th century), Schneeberg (1420), Altenberg (1440), St. Andreasberg (1480), Annaberg (1495), and Joachimsthal [Jáchmov] (1516).

Because of these discoveries, the CEMB became “one of the richest and most prosperous districts in Europe. Populous cities sprang up in all directions and the number of men from the mining centres who rose to distinction in all walks of life showed that the development was not one of wealth and material prosperity only, but also of the high civilization and culture. … Not only were advances made … in the technology of mining, ore dressing and metallurgy but also … there was accumulated a great body of knowledge connected with the geological sciences. It was here that the science of mineralogy ... took its rise” (Adams, 1938, p. 70). Examples of the profound influence that mining prosperity produced in the region during the Renaissance  include Martin Luther, the theologian and initiator of the Protestant Reformation, from Wittenberg, and the musical geniuses Bach and Wagner from the Leipzig area, and Handel from the Harz Mountains.

Increased economic activity created a growing market for metals, and the need to mine deposits to greater depths resulted in new inventions and new geological ideas. From an economic geology standpoint, De Ortu et Causis Subterraneorum, which has never been translated into English, is perhaps the most valuable of Agricola’s books because it contains his ideas on the origin of metals. He was the first to state two fundamental principles of ore deposition, namely that ore channels are younger than the enclosing rocks and that the ore minerals were deposited from solutions. He also divided mineral deposits into three types: fissure veins, bedded deposits, and impregnations. His most important contribution was his theory that there are two types of water within the crust, vapour of subterranean origin and rainwater, both of which become impregnated with mineral matter and become ‘lapidifying juice’ (nobilis succus) that deposits metallic minerals in cracks and fissures as veins. His treatise contained the germ of two ideas that took more definite form 300 years later, ascending water and lateral secretion (Adams, 1938). Agricola’s simple theory was remarkably close to modern understanding. Hoover and Hoover (1912, p. 52) considered it to be “a much greater step from what had gone before than that of almost any single observer since,” and felt that his main error was in attributing the creation of ore channels to erosion alone.

Economic geology seemed poised for great breakthroughs. One scientist mentioned by Adams, Johann Joachim Becher (1635-1682), published a perceptive theory in Frankfurt in 1653 that was sadly ignored. He believed that the centre of the earth was intensely hot, that the heat acted on saline water to produce immense volumes of steam and exhalations, and that these were forced through pores and fractures to surface. Pure vapours would produce fresh spring water, impure vapour would produce saline springs, and other fumes that contained a ‘metallic seed’ would condense in fissures and pores in the form of metallic ores. He also postulated that mineralization would become more abundant with depth. With Agricola, Becher, and other leading scientists developing theories to explain the ever-increasing body of information that was accumulating from the study of the mines, it seemed inevitable that the link between mineralizing fluids and igneous and volcanic heat and fluids would be recognized as advances in chemistry allowed.

During the late 16th and 17th centuries, when Latin America was becoming the silver capital of the world and Cornwall was beginning to dominate the production of tin and copper, German scientists, teachers, and mining experts failed to capitalize on this opportunity. Because of that, over 200 years would pass after Agricola’s death before significant discoveries would be made in other parts of Europe on the genesis of mineral deposits.  The most influential German geologists made two serious errors.  First, they failed to recognize the volcanic rocks in the CEMB because they didn’t travel enough to recognize the similarities to obvious volcanoes such as Etna and Vesuvius in Italy.  The columnar basalt flows in Germany are interbedded with sediments and were misinterpreted as part of the sedimentary succession.  This mistake was partly related to the second error, an overriding belief by the most influential German geologists in the Great Deluge, a principal tenet of the Book of Genesis.  Belief in the idea that all mineralization was precipitated from seawater prevented them from taking the theory of ascending mineralizing fluids seriously.

Few economic geologists have ever heard of the little-known scientists and naturalists, mostly French and British, who played key roles in recognizing the origin of basalt and realizing the importance of igneous processes.  Their contributions to the science of economic geology will be described following a revisit to Cornwall, where German mining expertise was imported to enable underground mining to proceed.


ADAMS, F.D., 1938. The Birth and Development of the Geological Sciences. Dover, New York.

AGRICOLA, G., 1556. De Re Metallica. Froben Press, Basle. Translated into English by H.C. Hoover and L.H. Hoover. Mining Magazine, London, 1912 (reprinted by Dover Publications, Inc., New York, 1950).

CHAMPLIN, P., 1998. Economic Geology. In Sciences of the Earth: an Encyclopedia of Events, People and Phenomena.  Edited by G.A. Good. Garland Publishing Inc., New York, p. 225-226.

HOOVER, H.C. and Hoover, L.H., 1912. Introduction, in their English translation of Agricola’s De Re Metallica. Mining Magazine, p. vi-xviii.

LINDGREN, W., 1913. Mineral Deposits. McGraw-Hill Book Company, New York, p. 1.

LONG, P.O., 2006. Available at: muse.jhu.edu/demo/technology_ and_culture/v044/44.1long.pdf.

SEG, 2006. Available at: www.segweb.org.

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