Ore Mountain Mining Region recognised as a UNESCO world heritage site - for which it has been nominated - it should help to preserve it for future generations as a "developing cultural landscape". From the first discovery of silver ore in 1168 in Christiansdorf in the territory of the present-day borough of Freiberg, which is part of the Freiberg Mining Field, mining was carried out uninterruptedly in the Ore Mountains until 1990. Amongst the raw materials mined over the course of centuries were ores of the metals silver, tin, zinc, cobalt, nickel, copper and lead; but anthracite and uranium were also extracted into the
Pitinga mine By 1990 the mine directly employed 2,000 people, and indirectly perhaps as many as 40,000. Trees were cleared, the river diverted and dams and ponds built before the alluvium deposits were processed. Bucketwheel excavator dredges extracted material rich in cassiterite, which was pumped through pipes to floating processing plants that separated the tin ore. The cassiterite is concentrated on site, then shipped to Mamoré Mineração e Metalurgia in the southern state of São Paulo for casting. Columbite ore is also mined, concentrated and processed on site for use in production of FeNbTa metallic alloy. Up to 1990 a total of