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Georgius Agricola (1494-1555), whose real name , was Georg Bauer, was trained first as a philologist, then as a physician. Born in Glouchau, Saxony, Germany, Agricola studied at Leipzig, Bologna, and Padua and received his MD degree from the University of Ferrara in 1525.

In 1526, he was appointed city physician of the flourishing mining town of Joachimsthal in Bohemia. While there, he became interested in ores and metals and compiled his De Re Metallica, which he wrote in 1530 but which was not published until 1556. As a result of this work, Agricola became known as "the founder of scientific mineralogy." His publication also contained much new material in chemistry and medicine and is one of the first works after the Middle Ages to return to the natural science tradition of Pliny. Among his other writings is a description of scurvy in 1539 and an early study of numismatics. From 1534 until his death, he practiced in Chemnitz in Saxony.
Philatelically, he was honored as the first modern metallurgist on a stamp (Scott No. 271) issued by East Germany in 1955 on the 400th anniversary of his death.

(By -M. A. Shampo and R. A. Kyle, JAMA, Nov 3, 1975-Vol 234, No 5)

 

In Speleo Stamp Collector magazine number 10 (1983) published Jan Paul van der Pas
a few notes about Agricola and Caves, based on a book  'History of Cave Science' by Trevor R. Shaw. In this book are a several researchers mentioned who also did some cave-related work. All the following facts are taken from this book.

Earliest known description of a form of cave pearl)*: 'Stones have been found near the hot springs of Karl the Fourth composed of a large number of units cemented together. The units are as poreus as a honey-comb, hemispherical and the size of a pea. They are formed from dripping hot water'.
)*pisolites at the hot springs of Kalovy Vary

About cave coral: 'A stone is found in a water course inside a cave... , with a dark color, tabular form, as harsh as a Sal ammoniac and having protuberances on the upper surface that resemble the heads of nails’.

About mondmilch: the example he saw ,was in a quarry, not a cave, and he calls it Steinomarga.

He developed quite independently his idea of a succus lapidescens to explain the formation of minerals and certain rocks including stalactites.

'Stones which form in caves from juices that drip from the roof and harden, because of the cold, are also called tofus'. Some of the deposits, the ones described as tofus or tufa because of their porosity, are in fact soft and fragile, he said. Others are hard like marble, 'transluctant and with a fine lustre even though they have not been polished'. He cited examples of these, both white and reddish, in the Einhornhöhle near Scharzfeld in the Harz mountains.

...was accounting for the origin of caves by the erosive power of water significantly...