Cross and Hillebrand—Cryolite from Colorado. 277 
fect intergrowth of pachnolite individuals in three directions 
pproximately at right angles to each other. Nearly simulta- 
ent individuals. Such a structure is also illustrated by the 
Y could seldom be distinctly seen. Many crystals are some- 
i i em 
what extended parallel to one pair of prism faces. ior- 
thodome of the same order as pyramid is sometimes devel- 
oped and probably corresponds to that notice h 
covered by minute erystals of a later growth to be available 
or measurements with the goniometer. @ 
_ Whether thomsenolite is mixed with pachnolite in the mas- 
Sivé portion or not is difficult to determine. It is certainly in 
comparatively small quantity if present, and in the cavities all 
the recognizable crystals are deposited upon the pachnolite and 
INVestigation. ‘ 
The first of these, which we will designate specimen A, 18 
about 8x5x2™ in size, is somewhat more coarsely granular 
than the variety described, and possesses in an eminent degree 
the regular structure there observed. While quite compact 
in the greater part of the specimen there are portions in which 
the grains are more loosely aggregated together and parts of 
