The Collaborative International Dictionary of English v.0.48:

Pyrites \Py*ri"tes\, n. [L., fr. Gr. ?, fr. ? fire. See Pyre.]
   (Min.)
   A name given to a number of metallic minerals, sulphides of
   iron, copper, cobalt, nickel, and tin, of a white or
   yellowish color.
   [1913 Webster]

   Note: The term was originally applied to the mineral pyrite,
         or iron pyrites, in allusion to its giving sparks when
         struck with steel.
         [1913 Webster]

   Arsenical pyrites, arsenopyrite.

   Auriferous pyrites. See under Auriferous.

   Capillary pyrites, millerite.

   Common pyrites, isometric iron disulphide; pyrite.

   Hair pyrites, millerite.

   Iron pyrites. See Pyrite.

   Magnetic pyrites, pyrrhotite.

   Tin pyrites, stannite.

   White iron pyrites, orthorhombic iron disulphide;
      marcasite. This includes cockscomb pyrites (a variety of
      marcasite, named in allusion to its form), spear pyrites,
      etc.

   Yellow pyrites, or Copper pyrites, the sulphide of copper
      and iron; chalcopyrite.
      [1913 Webster] Pyritic

The Collaborative International Dictionary of English v.0.48:

Arsenopyrite \Ar`sen*o*pyr"ite\, n. [Arsenic + pyrite.] (Min.)
   A mineral of a tin-white color and metallic luster,
   containing arsenic, sulphur, and iron; -- also called
   arsenical pyrites and mispickel.
   [1913 Webster]