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
Germanium to be AgGeS. Because this new element showed some similarities with the elements arsenic and antimony, its proper place in the periodic table was under consideration, but its similarities with Dmitri Mendeleev's predicted element "ekasilicon" confirmed that place on the periodic table. With further material from 500 kg of ore from the mines in Saxony, Winkler confirmed the chemical properties of the new element in 1887. He also determined an atomic weight of 72.32 by analyzing pure germanium tetrachloride (), while Lecoq de Boisbaudran deduced 72.3 by a comparison of the lines in the spark spectrum of the element. Winkler