Cross and Hillebrand—Cryolite from Colorado. 273 
mile apart, and their continuation is so concealed by soil and 
debris that it cannot be seen what their relation to each other 
and to the other veins may be. They differ, however, so 
greatly in the minerals they contain and in the manner of oc- 
currence of the latter, as t) make it improbable that they are 
nited. 
n the vein which we will designate vein A, cryolite, pach- | 
nolite, thomsenolite, gearksutite, prosopite and probably ralsto- 
nite appear, with but rare associated minerals. In vein B, on 
the other hand, prosopite, fluorite and mixed fluorides occur 
intimately associated with zircon, kaolinite and a greenish yel- 
low mica. As the minerals of the two veins are so distinct, we 
can best consider them in the groups afforded by the veins 
themselves. 
VEIN A. 
and below it came massive quartz again. The boundaries of 
this mass are quite irregular, and its lateral extent is still 
which is not homogeneous and whose composition is unknown. 
at astrophyllite springs from the granitic wall of the vein in 
With it in the mass at the base of the blades, while never seen 
imbedded directly in the cryolite. The columbite is in small, 
rhombic prisms of the type found with the Amazon stone, and 
r 
Position products adjacent to the astrophyllite will be described 
ater (page 289), 
. Adjoining the quartz, the cryolite is always decomposed, and 
1S generally replaced by a massive mixture of pachnolite and 
thomsenolite, but not infrequently the alteration bas gone still 
minerals will begin with eryolite and proceed through the 
different stages of alteration here exhibited. 
