An Etymological Dictionary of the German Language/Erz
Erz, n., ‘ore, metal, brass, bronze,’ from the equiv. MidHG. ęrze, arze, OHG. ęrizzi, aruzzi, aruz, n.; an obscure word, which is unknown to the other Teut. dialects; probably borrowed under the form azuti, arwuti?. In Goth. ais, AS. âr, E. ore, OHG. and MidHG. êr, ‘bronze,’ whence the OHG. and MidHG. adj. êrîn, ModHG. ehern; these are primitively cognate with Lat. aes, ‘bronze,’ and Sans. ayas, ‘metal, iron.’