Letters of Johann Jacob Ferber Geological descriptions of Slovenia from second half of 18th century

The two translations of letters by Johann Jacob Ferber (1743–1790), a Swedish geologist and mineralogist, who travelled through Slovenia in September 1771, are discussed. The first letter addressed to Ignaz von Born was published in the book »Briefe aus Wälschland über natürliche Merkwürdigkeiten dieses Landes an den Herausgeber derselben Ignatz Edlen von Born« published in Prague in 1773, and the second letter to Giovanni Arduino was published in the book »Raccolta di memorie chimico-mineralogiche, metallurgiche, e orittografiche« published in Venice in 1775. Both letters represent an Enlightenment scientific description of the geology of part of what is now Slovenia, based on the geological theories valid at the time. In the article, we provide brief biographies of the actors, translations of the two letters, their commentary and interpretation.