Sala Silver Mine
Sala Silver Mine (Swedish: Sala silvergruva) is a mine in Sala Municipality, in Västmanland County in Sweden. The mine was in continuous production from the 15th century until 1908. Additional mining occurred in 1950-1951 and also in 1945-1962 in the neighboring Bronäs Mine.
The Sala ore is mainly known for its high silver content though the ore also contained economic amounts of lead and zinc. The zinc was hosted by the mineral sphalerite while lead was hosted by the mineral galena. Silver occurred as a native phase rarely but was mainly hosted by complex antimonides and sulphosalts, dispersed in the matrices of galena and sphalerite, invisible to the naked eye but visible in microscope. The silver content in typical galena-dominated Sala ore was about 0.15% to 1%, the latter being one of the highest contents of silver in galena ever reported. In the sphalerite-dominated ore, the silver content is only about 0.015-0.02%, which was still enough to exploit and would even be at present days, given that a sufficient tonnage of metallurgically advantageous ore could be found.
The bedrock was created about 1,89 billion years ago during the paleoproterozoic era. The host rock to the mined ore is dominated by white dolomitic marble, proximal to the ores commonly rich in skarn minerals such as tremolite, serpentine, diopside and chlorite, giving the dolomitic marble at Sala a characteristic green colour. ~ 100 meters away from the mine, more pure white dolomitic marble poor in skarn minerals is extracted at the Tistbrottet dolomite quarry.