Cross and Hillebrand—Cryolite from Colorado. 289 
orm is here quite obscure, but the general appearance was 
80 suggestive of.prosopite that by sacrificing the best specimen 
enough material was obtained for determination of the bases 
and of fluorine, with the result given below—V, p. 29 
Vern B. 
Deseription.-The minerals found in this vein have been 
exposed by the “Eureka” tunnel which has been driven in 
upon it for one hundred feet or more. Unfortunately the walls 
crystals are imbedded largely in the quartz itself and to a less 
ree in compact, white kaolinite, a greenish yellow mica, and 
