Latin - the universal language
Agricola wrote De Re Metallica in Latin, not his native German, in order to reach an international audience, as Latin was the universal language.
It was used throughout Europe for scholarly and scientific writing and was the language of international diplomacy.
To help him devise new names for processes and equipment in Latin Agricola looked at the Naturalis Historia by the first-century A.D. Pliny the Elder.
For further reading regarding Pliny the Elder: http://www.livius.org/pi-pm/pliny/pliny_e3.html
Image of Latin from the text: Book 1, page 1.
Extract reproduced from Georgius Agricola, De Re Metallica (Basel, 1556), p1
Digitised De Re Metallica
This link to the University of Oklahoma Libaries special collections provides access to some pages of the original De Re Metallica (1556) in Latin online.