Cross and Hillebrand—COryolite from Colorado. 283 
. . 
the crystals oceurring as described, is less than 1" in diam- 
eter, and no pure material even for qualitative tests can be 
obtained. 
e 
rounded, crystal-like projections, which seemed like crystals of 
the regular system. A 
absence of recognizable faces, but such particles when broken 
of and tested under the microscope, proved to be fully iso- 
tropic. A few faces found on one crystal seem to belong to 
_ *G. J. Brush, this Journal, III, ii, p. 30, 1871; also P. Groth, 1. ¢., p. 471. 
