|
836
|
MINERAL RESOURCES.
|
||
|
|
|||
|
PENNSYLVANIA.
George
0. Simmons, of Brooklyn, N. Y., reports the occurrence of small
ruby-red rutile crystals on quartz and rutilatcd quartz at Howard
House, Delaware County, Pa.
VERMONT.
George
Davidson, of South Royalton, reports the occurrence of a large deposit
of quartz in that region. A few specimens of crystals have been
obtained for cabinet use, and massive material has been sold for rough
specimens.
BRAZIL.
According to A. S. Atkinson0
the best quartz and rock ciystals of Brazil come from the Cristacs
Mountain in the State of Goyaz. The output has been large from this
region, and mining has been carried on for many decades. Undeveloped
deposits still exist. Yellow quartz is exported from Goyaz and is sold
in considerable quantity for cheap jewelry. It resembles topaz and is
sold for that mineral.
ROSE QUARTZ.
SOUTH DAKOTA.
Rose
quartz of a more or less pale color is found at numerous places in the
Black Hills. It is associated with the pegmatitic rocks of the region
and is found at several of the mica mines. Material suitable for gem
purposes has been mined in quantity at the Red Rose mine only. The
latter mine is 6-1/2 miles S. 50° E. of Custer in a small gulch
draining into French Creek. The mine was first taken up some years ago
by a Mr. Demerau and was sold to eastern parties for §300. After the
claim was allowed to revert it was relocated and is now held by Samuel
Scott, of Custer.
The
operation of obtaining rose quartz at the Scott mine consists simply in
blasting the massive quartz from the face of a large ledge and
selecting the material of suitable quality. The rose quartz occurs in a
ledge 6 to 15 feet thick that stands from 10 to 30 feet high along the
south wall of a small gulch. It outcrops for a distance of over 100
yards and is found at points 200 yards apart. The quartz is part of a
large pegmatite which has an east and west strike and cuts directly
across the schistosity of the cyanite-muscovite-biotite gneiss country
rock with a steep dip. The strike of the gneiss on the south side of
and close to the pegmatite is about north and south with a vertical
dip. Part of the quartz is white; a large part is pale rose; some is of
a rich dark rose color, and some has a purplish rose tint. The dark
rose color occurs through the quartz over areas 10 to 12 feet across.
Solid clear translucent to transparent flawless rose quartz of deep
color is obtained in pieces up to 2 inches in diameter. The greater
part is more or less checked with flaws, or is marked with cloudy lines
running through the quartz in various directions. These lines represent
joint planes, the walls of which have been firmly cemented together
again with quartz. In many cases these seams resist fracturing as
strongly as the solid quartz, so that they do not impair the strength
of gems cut from such material. One prominent
" Mining for gems in Brazil: Eng. and Min. Jour., Juno 19,1909.
|
|||
|
|
|||