74 
ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
As an alteration product of the wall rock, more particularly of the 
feldspathic constituents, kaolinite is extremely common; but it is 
often impossible, without a chemical analysis, to distinguish it from 
sericite. Both minerals occur in similar fine aggregates, and they 
sometimes occur together. In such cases the microscope will not 
always serve to distinguish them. 
Fluorite. — CaFl ? . Isometric. Massive, or in variously modified 
cubes and octahedra. Cleaves in four directions, forming octahedra. 
Colorless, or pale green or lilac. Hardness, 4. Specific gravity, 3.1. 
Pale-green fluorspar is abundant on some of the dumps of the Aspen 
Fig. 
Diagram illustrating common occurrence of kaolin in the Red Mountain region, 
kaolin is traversed Ly a network of pyrite. From Zufii mine. Natural scale. 
The 
mine, but was not seen in place. In a massive condition it forms a 
vein which has been superficially prospected on the north side of Pic- 
ayune Gulch, near its mouth, and was seen in a prospect near the 
Mountain Queen mine, in California Gulch, and in another prospect 
just east of Lake Como. It was also noted in the dump of the upper 
tunnel of the Micky Breen mine. Well crystallized with quartz, 
fluorite occurs in a prospect just north of the Old Lout mine, and in 
the Indiana tunnel in Grey Copper Gulch. In the Sunn}^side lode, 
fluorspar, usually of a lilac tint, accompanies the best ore and is used 
by the miners as an indicator for free gold. Pale-green fluorite occurs 
with calcite in the quartz of the Tomboy lode and as a microscopic 
