The Collaborative International Dictionary of English v.0.48:

Stannine \Stan"nine\ (-n[i^]n), Stannite \Stan"nite\
   (-n[imac]t), n. (Min.)
   A mineral of a steel-gray or iron-black color; tin pyrites.
   It is a sulphide of tin, copper, and iron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stannite
    n 1: a dark grey mineral with a metallic luster that is a source
         of tin [syn: stannite, tin pyrites]