12 October 1825 - Death of Franz-Joseph Müller, discoverer of tellurium

Franz-Joseph Müller von Reichenstein was born in Transylvania on 1 July 1740. He studied at the University of Vienna and the Mining Academy in Schemnitz, Slovakia, where he specialized in mineralogy and chemistry. After graduating he worked as a mining engineer in Hungary.

In 1782, Müller analyzed a bluish-gold vein in Transylvania known as 'Germanic gold'. He extracted the metal on the assumption that it was antimony but discovered that it had unique chemical properties and was an unknown element. However, he did not continue his research. Later, in 1789, the German chemist Martin Heinrich Klaproth isolated this new element and named it tellurium (Greek for 'earth' and 'distant'). Despite this, Müller is still credited with the discovery.

The discovery of tellurium, a non-metallic chemical element with the symbol Te and atomic number 52, was a significant milestone in chemistry. It is a relatively rare element but has a variety of applications, such as the manufacture of semiconductors, pigments, and pharmaceuticals.

Müller was also a leading mineralogist who identified and named several new minerals, including tourmaline, chrysoberyl, and opal. In addition, he was a member of the Vienna Academy of Sciences and the Royal Society of Edinburgh, received the Copley Medal of the Royal Society in 1809, and wrote several books and articles on mineralogy and chemistry.