Where does “Manganesium” come from?

Manganesium (German) comes from French manganèse, from Italian manganese, from New Latin magnēsium, from Ancient Greek Μαγνησία, from Ancient Greek -ῐ́ᾱ, from Proto-Indo-European -íh₂, from Proto-Indo-European -h₂ — Creates collective nouns, which refer to groups...