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MINERAL RESOURCES.
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RUSSIA.
Amber was discovered in Transuralia on the Isset River about a century ago.a
This deposit was in a brown coal formation, and since this coal
formation is now to be worked it is hoped new deposits of amber will be
found.
AMETHYST.
COLORADO.
A
deposit of cloudy amethyst has been worked in a small way in Fremont
County, 12 miles northwest of Canon City and 1 mile south of Twelvemile
Park. This deposit was opened some years ago by prospectors in search
of gold, the amethyst being mistaken for fluorite, which was considered
a good indication of that metal. In March, 1907, the claim was
relocated by J. D. Endicott, of Canon City, as a gem deposit. Three
openings have been made--a shaft 25 feet deep, a pit 15 feet deep, and
another pit 10 feet deep.
The
country rock is biotite granite gneiss whose schistositv strikes N. 40°
E. with a dip of 30° SE. Small dikes or veins of coarse granite or
pegmatite with dark red feldspars cut the granite gneiss. Some of these
dikelets are badly epidotized, with the result that the red feldspars
with yellowish-green epidote form a rock with a pleasing combination of
colors for small ornamental purposes. The amethyst is found in a vein
or system of veinlete, ranging from several inches to 3 feet in
thickness associated with a pegmatite streak. The amethyst occurs in
streaks and veinlets varying from less than 1 inch to 3 or 4 inches in
thickness and opening out into irregularly shaped pockets 8 or 10
inches across. The greater part of these streaks are vertical and
parallel to the walls of the veins, though in some cases they are
inclined and transverse to the vein. The veinlets are made up of layers
of amethyst and smoky quartz crystals with comb structure. Nearly all
the cavities have been completely filled with amethyst, so that few are
obtained with perfect crystal form. Pink calcite forms a part of the
vein filling in places. The wall rocks have been partly decomposed and
hardened by silicifica-tion. The order of formation of parts of the
vein appear to be: Fissuring, silicification of wall rock, deposition
of calcite, more fracturing, deposition of smoky quartz, deposition of
amethyst, deposition of shells of white quartz or amethyst crystals.
The
cloudy amethyst is translucent, with patches of deep amethyst color
scattered through paler portions. When cut "en cabochon" or in beads
this gem is very attractive for scarf pins, cuff buttons, or necklace
stones. It is probable pieces of sufficient size could be obtained for
umbrella handles or similar small ornaments, as some of the crystals
are 2 inches thick.
PENNSYLVANIA.
Dr.
Edgar T. Wherry, of Lehigh University, reports the occurrence of
amethyst at several localities in southeastern Pennsylvania. Crystals
of fairly good color, though generally somewhat cloudy, are found on the farm of a Mr. Coppie about 1 mile
east of Media, Delaware County. These crystals of amethyst occur in
pockets in decomposed mica schist and are sometimes as much as 2 inches
long.
a Min. Jour. London, October 17, 1908.
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