Franz-Joseph Müller, Freiherr von Reichenstein or Franz-Joseph Müller von Reichenstein was an Austrianmineralogist and mining engineer. Müller held several positions in the Habsburg Monarchy administration of mines and coinage in the Banat, Transylvania, and Tyrol. During his time in Transylvania he discovered tellurium in 1782. In his later career he became a member of the imperial council in Vienna and was knighted and elevated to the rank Freiherr in 1820.
He studied philosophy and law in Vienna. After finishing his studies he started further studies at the Bergakademie in Schemnitz, Lower Hungary in 1763. He studied mining, mechanics, mineralogy and chemistry and after graduating he became a Markscheider in 1768. In 1770 he joined the Hofcommission für die Regulierung der Banater Berg und Hüttenwerke where he gained a lot of knowledge on mining in the Banat. He was promoted to the rank of an Oberbergmeister and became a mine manager in the same year. In 1775 he became Oberbergmeister in the Tyrol town of Schwaz. Schwaz was one of the largest centres of silver and copper mining in Austria-Hungary in that time. In 1778 he discovered an occurrence of tourmaline in the Zillertal. Müller became one of seven Thesaurariats councillor in Transylvania responsible for the supervision of all mining and coinage activities in Transylvania in 1778. After the dissolution of the Thesaurariat Müller became Oberinspector of all mining, smelting and salt production in Transylvania.
Discovery of tellurium
Müller as the Austrian chief surveyor of mines in Transylvania was responsible for the analysis of ore samples. He analyzed gold ore from Kleinschlatten. This ore was known as "Faczebajer weißes blättriges Golderz" or antimonalischer Goldkies, and, according to Anton von Rupprecht, was Spießglaskönig, containing native antimony. Müller concluded that the ore did not contain antimony, but that it was bismuth sulfide. The following year, he reported that this was erroneous and that the ore contained mostly gold and an unknown metal very similar to antimony. After a thorough investigation which lasted for three years and consisted of more than fifty tests, Müller determined the specific gravity of the mineral and noted the radish-like odor of the white smoke which passed off when the new metal was heated, the red color which the metal imparts to sulfuric acid, and the black precipitate which this solution gives when diluted with water. Nevertheless, he was not able to identify this metal and gave it the names aurum paradoxium and tlbermetallum problematicum
Later life
In 1788 he was once more promoted and as Gubernialrath he held a powerful position in the administration of Transylvania. Müller was knighted by Leopold II to the lowest title of nobility, Edler, in the same year. From that point on he carried the name Franz-Joseph Müller Edler von Reichenstein. He was elected as a member of the Berlin Society of Friends of Natural Science. In 1798 Müller became court counsellor and was appointed to the court in Vienna, where he was part of the imperial council. In 1818 Müller retired from his duties but held his position in the council until his death. He became Knight of the Order of Saint Stephen of Hungary in 1818 and became a noble by receiving the title of a Freiherr in 1820. Both honours were granted by the Emperor Franz I. Müller died in his 80s in 1825 or 1826 in Vienna.
