zinc-orehttp://www.oed.com/dictionary/zinc-ore_n%3Ftab%3Dmeaning_and_usezinc ore, n.
First published 1921; not fully revised

zinc orenoun

  1. 1808–
    1. 1808
      Gahnite..a species of zinc ore.
      T. Allan, Alphabetical List Minerals 33
    2. 1839
      The mineral genus called zinc-ore..is denser than either of the above.
      A. Ure, Dictionary of Arts 1330

Originally published as part of the entry for zinc, n.

zinc, n. was first published in 1921; not fully revised.