The Collaborative International Dictionary of English v.0.48:

Helvine \Hel"vine\, Helvite \Hel"vite\, n. [L. helvus of a light
   bay color.] (Min.)
   A mineral of a yellowish color, consisting chiefly of silica,
   glucina, manganese, and iron, with a little sulphur.
   [1913 Webster]