The Collaborative International Dictionary of English v.0.48:

Fahlband \Fahl"band`\, n. [G., fr. fahl dun-colored + band a
   band.] (Mining)
   A stratum in crystalline rock, containing metallic sulphides.
   --Raymond. Fahlerz

The Collaborative International Dictionary of English v.0.48:

Fahlerz \Fahl"erz\, Fahlband \Fahl"band\, n. [G. fahlerz; fahl
   dun-colored, fallow + erz ore.] (Min.)
   Same as Tetrahedrite.
   [1913 Webster]