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

Auriferous \Au*rif"er*ous\, a. [L. aurifer; aurum gold + ferre
   to bear: cf. F. aurif[`e]re.]
   Gold-bearing; containing or producing gold.
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         Whence many a bursting stream auriferous plays.
                                                  --Thomson.
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   Auriferous pyrites, iron pyrites (iron disulphide),
      containing some gold disseminated through it.
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