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Idrija -- historical notes

In the beginning, ore was smelted in ceramic pots in the surrounding hills (in a kind of coke piles) because this was easier than transporting masses of wood to Idrija. But then too much mercury got stolen...

Mercury was first exported via Venice to Levante, and later also to Germany and Holland, to be further exported to Mexico and Peru for use in amalgamation in silver and gold mines there. Since 1659 Amsterdam was the main export center. In 1785-1797, up to 700 tons of mercury were exported to Spain yearly.

A castle (now housing the Museum) was erected 450 years ago to protect mercury against possible attacks by the Turks who roamed Europe at that time.

The world use of mercury peaked around 1968. According to the 1968 US data, of the total of 2500 tons, 600 tons were used in chlorine and caustic soda production, 600 tons ended up in batteries and light bulbs, 380 tons in control instrumentation, 360 tons as color additives, 141 tons in people's teeth, 120 tons in agricultural fungicides, 13 tons were used in paper and cellulose industry, etc. Cinnabar is a well known dye; mercury chloride was used as antiseptic even in this century.

The mining operation was a textbook case of full utilization of the wood and water resources in the river Idrijca basin, without actually destroying either, except very close to the smelting operation.

Several water dams for floating timber were built in remote valleys called Klavze (from latin for dam). Starting in 1767, the local engineer Jozef Mrak finished the first Klavze made of stone in the Belca valley (1769) and in the Idrijca valley (1772), and repaired some others. They had wooden doors that were flung open to produce a rushing wave sweeping the valley below and carrying the year's lot of timber towards Idrija. Timber was collected in the town by wooden combs across the river, the first of these having been constructed in 1531.

The mine was drained by several water-driven pumps. Restored in 1994 is the largest still existing water wheel in Europe: popularly called Kamst (from German, Kunst, for art), 13.5 meters in diameter, built around 1790, and driven by water from the Idrijca river, it was pumping water from from a depth of up to 300 meters without interruption for 160 years, until 1948, after the WWII! Already in 1665 the Englishman Walter Pope wrote he had never seen water wheels as large as those used in Idrija.

In the 16th century, Paracelsus visited Idrija and introduced mercury in medicine. Joannes Antonius Scopoli served as medical doctor in Idrija from 1745 to 1769. (1761 is the year of the first lace and of the work by Scopoli: De Hydrargyro Idriensi.) Balthasar Hacquet, who also wrote the Oryctographia Carniolica, lived in Idrija from 1766 to 1773; at that time, Idrija was the second largest town in Carniola.

The riddle of the Idrija ore deposit (its origin and structure) was fully solved only after WWII by Ivan Mlakar, who in doing so established the internationally acclaimed Idrija geological school.

From various sources; with thanks to Darko Viler.

R. Krivec