Mining is a dirty business! Presious metals mining, in particular silver mining, has always been the worst ecologically dangerous disaster of our planet.
The are few major devastating facts about silver mining. One of them is a use of toxic metals in minig. These metals are used to substruct silver from ore. Mercury is the most toxic metal that has been used in silver and gold mining for centuries. The annual loss of mercury in the silver mines of Spanish America averaged 612 tonnes/year (range 292-1085 tonnes/year) between 1580 and 1900. The production and importation of mercury into the United States ranged from 268 to 2820 tonnes/year and averaged ~1360 tonnes/year between 1850 and 1900. Approximately 90% of the mercury consumed in the United States during this period was employed in gold and silver extraction. The cumulative losses of mercury to the environment due to the production of precious metals in the Americas totalled ~257 400 tonnes, with 196 000 tonnes dispersed in South and Central America and 61 380 tonnes in the United States. Approximately 60-65% of the mercury lost is believed to have been released to the atmosphere and water, suggesting that gold and silver mines were a dominant source of atmospheric mercury pollution. Because of its high volatility, any deposited mercury can readily be re-emitted to the atmosphere.
Recent economical and social situation mostly in developing countries and increase in price of precious metals resulted in a new rush for gold and silver mining by individual entrepreneurs for whom Mercury emalgamation is a cheap anf easy way to carry out their operations. The new rush has spread mainly over Amazonian countries in particular Venezuela where many rivers were deforested by 35,000 miners since 1990...

Here are some known facts about impact of modern presiouse metals minig to our planet's environment:

Operated jointly by an Australian and Romanian mining companies, Baia Mare reprocessed mine waste from earlier activity to recover gold, silver and other metals.
In January 2000, the tailings impoundment dam failed, resulting in the release of 130 cubic yards of mine waste contaminated with cyanide and heavy metals. Result was disruption of drinking water supplies in 24 locations and for 2.5 million people and massive fish kill in the Tisza River

Sumary:
Environmental and Public Health Impacts
On January 30, 2000, as a result of snow and rain, water in the tailings impoundment overtopped the dam, resulting in a break in the dam. One hundred and thirty cubic yards of mine waste containing approximately 75 tons of cyanide flowed into the Sasar River, and then into the Somes. The Somes is a branch of the Tisza river, the second largest river in Hungary. All of these rivers are part of the larger Danube River system. In all, over 1,200 miles of the Danube River system were contaminated. The spill threatened the drinking water supplies of 2.5 million people and caused enormous damage to wildlife in Hungary and Yugoslavia. It was estimated that 80% of all fish in the Tisza River died as a result of the spill. As CNN reported on February 14, 2000,