The Collaborative International Dictionary of English v.0.48:

Sinopite \Sin"o*pite\, n. [F., fr. L. sinopis (sc. terra), a red
   earth or ocher found in Sinope, a town in Paphlagoma, on the
   Black Sea, Gr. ????.] (Min.)
   A brick-red ferruginous clay used by the ancients for red
   paint.
   [1913 Webster]