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
Tantalum pentoxide tantalite are called coltan. Tantalite was discovered by Anders Gustaf Ekeberg at Ytterby, Sweden, and Kimoto, Finland. The minerals microlite and pyrochlore contain approximately 70% and 10% Ta, respectively. Tantalum ores often contain significant amounts of niobium, which is itself a valuable metal. As such, both metals are extracted so that they may be sold. The overall process is one of hydrometallurgy and begins with a leaching step; in which the ore is treated with hydrofluoric acid and sulfuric acid to produce water-soluble hydrogen fluorides, such as the heptafluorotantalate. This allows the metals to be separated from the various non-metallic