Agricola , Georgius

(1494–1555) German metallurgist

Agricola's true name was Georg Bauer but, as was the custom of the day, he latinized it (Agricola and Bauer both mean ‘farmer’). Beyond his place of birth – Glauchau (now in Germany) – little is known about him until his entry into the University of Leipzig in 1514. He later pursued his studies of philosophy and medicine in Italy at Bologna, Padua, and Venice (1523–27). In 1527 he was engaged as physician to the Bohemian city of Joachimsthal – the center of a rich mining area – moving in 1534 to another celebrated mining town, Chemnitz, near his birthplace. Here he became burgomaster in 1545. He wrote seven books on geological subjects but these were so illuminating of other subjects that he was known in his lifetime as ‘the Saxon Pliny’.

His most famous work, De re metallica (1556), concentrates on mining and metallurgy with a wealth of information on the conditions of the time, such as management of the mines, the machinery used (e.g. pumps, windmills, and water power), and the processes employed. The book is still in print having the unique distinction of being translated and edited (1912) by a president of the United States, Herbert Hoover, with Lou Henry Hoover (his wife).

Agricola is often regarded as the father of modern mineralogy. In the Middle Ages, the subject was based on accumulated lore from the Orient, the Arabs, and antiquity. Stones were believed to come in male and female form, to have digestive organs, and to possess medicinal and supernatural powers. Agricola began to reject these theories and to provide the basis for a new discipline. Thus in his De ortu et causis subterraneorum (1546; On the Origin and Cause of Subterranean Things) he introduced the idea of a lapidifying juice (or succus lapidescens) from which stones condensed as a result of heat. This fluid was supposedly subterranean water mixed with rain, which collects earthy material when percolating through the ground.

Agricola also, in De natura fossilium (1546), introduced a new basis for the classification of minerals (called ‘fossils’ at the time). Although far from modern, it was an enormous improvement on earlier works. Agricola based his system on the physical properties of minerals, which he listed as color, weight, transparency, taste, odor, texture, solubility, combustibility, and so on. In this way he tried to distinguish between earths, stones, gems, marbles, metals, building stone, and mineral solutions, carefully describing his terms, which should not be assumed to be synonymous with today's terms, in each case.