Bernic Lake is a lake in the eastern part of the province of Manitoba, Canada. It is located just southwest of Nopiming Provincial Park, and just north of Whiteshell Provincial Park.
Tanco Mine or Bernic Lake mine is an underground caesium and tantalum mine, owned and since 2019 owned and operated by Sinomine Resource Group on the north west shore of Bernic Lake, Manitoba, Canada. The mine has the largest known deposit of pollucite and is also the world's largest producer of caesium.
The mine has the largest tantalum reserves in Canada having estimated reserves of 2.1 million tonnes of ore grading 0.22% tantalum. The mine also has additional reserves amounting to 7.3 million tonnes of ore grading 2.76% lithium.
The pollucite (chemical formula (Cs,Na)2Al2Si4O12·2H2O) deposit associated with the pegmatite is the largest known deposit of this mineral and with 350,000 tons, it accounts for two thirds of the known resources. With an estimated average global use of 30,000 kg/year the reserves of the mine would last for 2,000 to 3,000 years. The mined pollucite contains approximately 24% Cs2O. The ore body is 1400 m long, 600 m wide and 100 m deep. For several decades the pegmatites at Bernic Lake have supplied the world with the needed caesium.
According to Wikipedia