The Collaborative International Dictionary of English v.0.48:

Sinter \Sin"ter\, n. [G. Cf. Cinder.] (Min.)
   Dross, as of iron; the scale which files from iron when
   hammered; -- applied as a name to various minerals.
   [1913 Webster]

   Calcareous sinter, a loose banded variety of calcite formed
      by deposition from lime-bearing waters; calcareous tufa;
      travertine.

   Ceraunian sinter, fulgurite.

   Siliceous sinter, a light cellular or fibrous opal;
      especially, geyserite (see Geyserite). It has often a
      pearly luster, and is then called pearl sinter.
      [1913 Webster] Sintoism
      Sintu
      Sinto