**2. Discovery of pitchblende and uranium**

Uranium minerals were noticed by miners in some silver ore deposits from the Ore Mts. area (Krušné Hory/Erzgebirge) for a long time prior the uranium discovery. The uranium mineral pitchblende was reported from this ore district as early as 1565. However, the miners have found that in places with higher occurrence of uraninite silver and its minerals disappear. The first occurrence of pitchblende entails trouble (pitch). Along with silver ores, some cobaltbearing minerals later were also mined, which were used for production of some enamels for glass and ceramic industry. In Jáchymov, main silver deposit on the Czech (Bohemian) side of the Ore Mts. area, the first enamel factory originated in 1780. After the discovery of organic ultramarine colours in 1828, the market for the more expensive cobalt colours was closed.

The German dispensing chemist Klaproth (1743–1817) had in his experimental laboratory in Berlin performed some experiments with pitchblende from the Johanngeorgenstadt uranium deposits in the Saxony. During these experiments in Berlin in 1789, Klaproth was able to precipitate a yellow compound (likely sodium diuranate) by dissolving pitchblende in nitric acid and neutralising the solution with sodium hydroxide. Klaproth assumed this yellow compound was the oxide of a yet-undiscovered element. By heating this substance with charcoal, he obtained a black powder, which he thought was the newly discovered element itself [1]. However, that powder was an oxide of uranium. Klaproth named the newly discovered element after the planet Uranus, which had been discovered eight years earlier by William Herschel. First sample of uranium metal was prepared in 1841 by Eugéne-Melchior Péligot, professor of analytical chemistry on the Central School of Arts and Manufactures in Paris, by heating uranium tetrachloride with potassium [2].
