The Collaborative International Dictionary of English v.0.48:

Bovey coal \Bo"vey coal`\ (Min.)
   A kind of mineral coal, or brown lignite, burning with a weak
   flame, and generally a disagreeable odor; -- found at Bovey
   Tracey, Devonshire, England. It is of geological age of the
   o["o]lite, and not of the true coal era.
   [1913 Webster]