The Collaborative International Dictionary of English v.0.48:
Spelter \Spel"ter\, n. [Cf. LG. spialter, G. & D. spiauter. Cf. Pewter.] (Metal.) Zinc; -- especially so called in commerce and arts. [1913 Webster]WordNet (r) 3.0 (2006):
spelter n 1: impure zinc containing about three percent lead and other impurities (especially in the form of ingots)