Source : Webster's Revised Unabridged Dictionary (1913)

Zinkenite \Zink"en*ite\ (-en*[imac]t), n. [From Zinken, director
   at one time of the Hanoverian mines.] (Min.)
   A steel-gray metallic mineral, a sulphide of antimony and
   lead.

Source : WordNet®

zinkenite
     n : a steel gray metallic mineral (a sulphide of lead and
         antimony)