The Collaborative International Dictionary of English v.0.48:

Pyrognostic \Pyr`og*nos"tic\, a. [Pyro- + Gr. ? to know.] (Min.)
   Of or pertaining to characters developed by the use of heat;
   pertaining to the characters of minerals when examined before
   the blowpipe; as, the pyrognostic characters of galena.
   [1913 Webster]