Post-transition metal defined transition elements as finishing at group 10 (nickel, palladium and platinum), therefore excluding group 11 (copper, silver and gold), and group 12 (zinc, cadmium and mercury). A survey of chemistry books in 2003 showed that the transition metals ended at either group 11 or group 12 with roughly equal frequency. Where the post-transition metals end depends on where the metalloids or nonmetals start. Boron, silicon, germanium, arsenic, antimony and tellurium are commonly recognised as metalloids; other authors treat some or all of these elements as nonmetals. The diminished metallic nature of the post-transition metals is largely attributable to the
Tellurium the planet. Tellurium-bearing compounds were first discovered in 1782 in a gold mine in Zlatna, Romania by Austrian mineralogist Franz-Joseph Müller von Reichenstein, although it was Martin Heinrich Klaproth who named the new element in 1798 after the Latin word for "earth", "tellus". Gold telluride minerals are the most notable natural gold compounds. However, they are not a commercially significant source of tellurium itself, which is normally extracted as a by-product of copper and lead production. Commercially, the primary use of tellurium is copper and steel alloys, where it improves machinability. Applications in CdTe solar panels and semiconductors also consume