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Public Radio's Environmental News Magazine (follow us on Google News)

Mercury’s Legacy

Air Date: Week of

A typical tunnel in one of the older parts of the mines. The ridges in the ground are for pit wagons, which were used to transport mercury ore out of the mine. (Photo: Chris Colin)

The town of Idrija, Slovenia, was built around mining mercury. At one time, it was home to the second largest mercury mine in the world. Today, the mines are shutting down permanently, but as Amy Standen reports, the legacy of mercury lives on.


CURWOOD: The town of Idrija, in the Balkan nation of Slovenia, was once home to one of the world’s largest mercury mines. For 500 years, miners pulled quicksilver out of this tiny valley, building a culture around – and, literally, on top of – this poisonous metal. Through the 18th and 19th centuries, scientists and doctors came from far and wide to study mercury mining and its effects on human health.

Now, with the use of mercury greatly reduced and a better understanding of its dangers the mines are in the process of being shut down. But as Amy Standen reports, the culture and toxic legacy of mercury mining remain.

STANDEN: Near the town square of Idrija, a man sells fish out of a trailer. It’s a sunny day, and a few of his customers hang around, as their cars idle. A stereo blasts Slovenian folk music.


A typical tunnel in one of the older parts of the mines. The ridges in the ground are for pit wagons, which were used to transport mercury ore out of the mine. (Photo: Chris Colin)

STANDEN: Standing here, you’d never guess there’s a whole other world beneath your feet – a vast network of tunnels, shafts and ladders long enough to stretch between LA and San Francisco.


STANDEN: The sign over the entrance to the Idrija mine reads “stre_no” or “good luck.” We walk through a tunnel carved out of rock, and then we begin our descent.


STANDEN: Down here, the tunnel is round and propped up with wood. It’s like walking through the inside of a barrel. The supports splinter and bulge under the weight of a thousand feet of dirt and stone above us.


DIZDAREVI: Yes, here you can see the drops, that sparkling.

STANDEN: Tatjana Dizdarevi is a mine safety engineer. She points to a cluster of perfectly shaped, silver caviar eggs that ooze out of the rock wall.

DIZDAREVI: These are drops of native mercury. If you will touch it with this golden ring, the mercury eat (Laughs), simply eat gold.

STANDEN: Idrija’s one of the few places on earth you’ll find elemental mercury like this. There’s also a more common form, cinnabar, a brick red mercury sulfide compound that must be cooked in a smelting plant to release its mercury content. Miners have hauled mercury ore out of these tunnels since 1490, only recently with elevators.

DIZDAREVI: They carried the ore in leather sacketts. Each miner by itself carried these sacketts and used wooden ladders to carry this very heavy material out. One piece of ore, a small piece, weighed almost five, six kilos. Depends on the percentage of mercury in it.

STANDEN: Smash or explode the rock. Gather and pack the ore. Carry it up and out to the smelting plant. This was the life of nearly every Idrijan male for 500 years.

Many miners and their families rented apartments in houses like these, with up to two families on each floor. (Photo: Chris Colin)

DIZDAREVI: My father was a miner, and I can remember from that time I was a little girl when he came home, at that time they worked in three shifts, also at night. It was very exhausting work. All the miners were tired. But these was almost the best paid jobs in the town.

STANDEN: Miners of Dizdarevic’s father’s generation didn’t live very long. Down in the mines, they handled pure mercury, which vaporizes at room temperature. Also toxic were mercury vapors coming from the smelting plant where concentrations were often highest.

Inhaled into human lungs, mercury vapors go straight to the central nervous system and the brain. Mercury poisoning contributed to alcoholism, depression, even suicide in many miners. Their hands shook so violently they could barely write.

KOBAL: When I come here at the beginning, this was something terrible to see what happened. I say what happened to these people? What they do in this mine?

STANDEN: Dr. Alfred Kobal spent his career treating miners. Slight and dapper, he seems proud of the work he’s done. Since coming here in 1964, Dr. Kobal has seen hundreds of mercury intoxications.

KOBAL: The people was so sad, sad. And we found that the mortality is connected to mercury exposure, and with alcohol consumption. And also you know and they smoke a lot of cigarettes a day. Altogether is the problem of miners.

This chapel, which stands at the start of the mines before miners begin their descent, was built in the 18th century. The chapel honors Saint Barbara, the patron saint of mining, and St. Ahac, on whose feast day, June 22nd, in 1508, miners discovered a rich new vein of mercury ore. (Photo: Chris Colin)

STANDEN: Miners were also exposed to radon, leading to high cancer rates, and silica dust, which filled their lungs with quartz crystals and, eventually, asphyxiated them. Dr. Kobal witnessed much of this suffering.

KOBAL: Short breath. Very difficult respiration. High amount of cough. They cannot move. They sit in the bath. They could not be horizontally in the bed, they must be sitting up all night. In the night was very long. I see many of these people who died due to this.

STANDEN: Thanks to Dr. Kobal and others, deaths like this became rare after the 1970s. Protective masks, air filters, and constant monitoring kept mercury vapors and silica dust levels far below what miners faced 50 years ago.

KOBAL: And these people live today. I see these people walk through Idrija and I am so glad that is so.

STANDEN: Even back when mortality was at its highest, Idrija was always a company town. The mine sponsored schools, gymnastics contests, Slovenia’s first theatre. It houses the town’s award-winning mining museum and launched the Idrija miners band, founded in 1665 and still going strong today.


STANDEN: Around the time the Idrija miner’s band started up, a British visitor took a dip here in the Idrica river. “The water is so saturated with mercury,” he wrote, “that it heals itchiness and other similar discomforts.”

Mercury occurs in the river naturally, in trace amounts, but the mine company dumped leftover ore on the riverbanks and sent mercury levels soaring.

Milena Horvat is a senior researcher at the Jo_ef Stefan Institute in Ljubljana. She’s studied the effects of mercury on the Idrijan environment for over 20 years.

HORVAT: We have in some areas deposits that are ten meters deep and still contain huge amounts of mercury.

STANDEN: Dr. Horvat says all this mercury would stay trapped within the Idrica River’s sediment, largely out of the food chain, if only people would let the river run its course. But local officials have a different plan.

HORVAT: Now they would like to build a new hydroelectric power plant on the Idrica river. This would be really a disaster because by stopping the water running in the Idrica river, you create a situation where methyl mercury is formed about 700 times higher rate than when you keep the water running. And if you increase methyl mercury in sediments in water, you increase it definitely in the fish.

STANDEN: Despite precautions taken at the mines, cancer, disorders of the central nervous and immune systems and other medical problems are still more common in Idrija than elsewhere in Slovenia. It’s as of yet unproven, but Dr. Horvat believes that elevated mercury levels in the air, soil, and water could have something to do with it. She wants to open a mercury information center in Idrija. She says the money’s there, but what’s lacking is community interest.

HORVAT: Because now when you go to Idrija everybody puts a lot of glory to the past of the mercury mining. It used to be the glory and it can remain the glory, but you really need to demonstrate that you know how to deal with this. Not to say “Oh! My grandfather was a miner, and I don’t care this mercury that is here in my environment, I don’t care.” It’s not possible to say this with all this evidence that we have today.


STANDEN: Meanwhile, about 60 miners are in the final stages of closing down the mines for good, filling in the tunnels with water, cement, and sand, so they don’t collapse. Car parts and electronics factories are the main employers in Idrija now. And while future generations will continue to reckon with mercury contamination, the industry that created it will soon be a distant memory.

For Living on Earth, this is Amy Standen in Idrija, Slovenia.



More info on Slovenian mines (1)

More info on Slovenian mines (2)


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