Written Mario Pleničar, 1989
Valvasor was the first to mention ore deposits in the territory of Slovenia. He wrote about Idrija where mercury was obtained, Malnek (Maljek) in the hills of Posavje, and about iron ore deposits and ironwork, which was a booming industry at that time. There is, of course, no reference to coal and coal mines, since it was only in the 18th century, and the early 19th, that the first coal mines were opened in this country.
Valvasor wrote extensively about the Idrija mine, the process of obtaining mercury and the diseases and habits of miners. Most of his attention, however, was devoted to iron, because Carniola used to be part of the Roman province Noricum, famed for steel production and products made of steel and iron, while ironwork in Bohinj may go back even to prehistoric times. Iron mines described by Valvasor were mainly deposits of “bobovec”, i.e., pisolitic bog iron. This had been collected for the needs of ironworks of Bohinj, Železniki, and Kropa since the 14th century. Similar kind of iron ore was collected also in Lower Carniola. In addition to deposits of pisolitic bog iron, which is relatively poor in iron content, Valvasor must have taken into account the iron ore deposits present in the Sava caves, which he referred to as the Sava mine. This ore was, according to Valvasor, “as white as the whitest alabaster”. In the Sava caves, the iron ore siderite is mined, consisting chiefly of iron carbonate, which is pale in colour; thus it may be concluded that it is the same ore deposit. It is also interesting to note that Valvasor mentions the first mining law in the country, which was passed by the emperor Ferdinand I in 1550.