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PRECIOUS STONES.
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829
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to
the vein and across it to the northwest. Sliekensides and evidence of
movement are more pronounced on the fissures parallel to the vein, and
two such prominent fractures form the walls of the vein through part of
its extent at least. The country rock is por-phyritic granite, badly
altered through kaolinization, portions of which form the mass of the
vein. A large amount of silicification has hardened the rock in many
places so that it does not resemble ordinary decomposed granite. This
silicification is represented by the deposition of quartz in part
throughout the rock and in part in seams and veinlets cutting it at all
angles.
Turquoise
occurs as veins and veinlets filling the joints and fissures in the
rock and as nuggets. In places these veinlets are mere films, and in
others they are as much as three-fourths of an inch thick. Part of the
turquoise is found in groups of small rounded masses resembling
nuggets, fitted roughly together though separated from one another by
kaolin or clay and enveloped in it. These groups of nuggets generally
fill a flattened lenticular-shaped pocket in one of the veinlets. The
best turquoise came from a portion of the vein known as the "Elizabeth
pocket," which extends from the second level to the surface, a height
of 40 to 60 feet, and may include a width of 40 feet and a length along
the vein of 150 feet. The vein rock near this pocket is cut by an
unusually large number of quartz seams and veinlets up to a half inch
wide. These contain crystal-lined cavities in places, and veins of
turquoise sometimes contain quartz crystals penetrating them. The
quartz veinlets sometimes give place to turquoise veinlets or include
patches of turquoise. Where portions of the rock are less altered and
pink feldspars occur, turquoise of a bright blue color is found.
Turquoise veinlets of different shades of color are found crossing each
other, indicating different periods of deposition and different sources
of material.
Good
turquoise was found at other places in the vein than in the Elizabeth
pocket. To the northeast or this pocket much of the turquoise had a
greenish cast, while still farther along good blue variety was more
plentiful. To the northeast of the open cut the Azure mine did not
yield much turquoise of good color in a drift several hundred feet
long. To the southwest of the open cut the vein is readily traced for
several hundred yards up Morrills Canyon. It contains very little
turquoise, however, but has been proved to carry fairly rich copper
ores. Mr. William R. Wade, who has directed the openings on this vein
for copper, reports that a little turquoise was found in the Copper
King mine at a depth of 410 feet. In the workings at the Azure mine the
best turquoise was found at depths of less than 100 feet. Pyrite or
sulphides were not observed associated with the turquoise, though the
wall rocks are colored red with hematite in places. Where the feldspars
of the rock have been the most extensively kaolinized turquoise is
found mostly in nugget form. In less altered rock hard vein turquoise
is found, and both varieties are found in moderately altered rock.
Mr.
Zalinsky mentions the various colors found in turquoise at the Azure
mine and the associations with other minerals and matrix. Nearly all
shades of blue and green occur—dark blue, sky blue, light blue, bluish
green, light green, and dark green—and in some cases reddish-brown,
chocolate, and violet-colored material has practically the same
composition as turquoise. A combination of colors
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