The Barre daily times. (Barre, Vt.) 1897-1959, 1913-09-29
WHERE oPALs ARE MINED.
Valuable Discoveries Have Been Made
in Nevada.

in Nevada.
/ Mention has been made of the opal de-
posits Of Virgin valley, Humboldt coun-
ty, New, in the chapter on precious
stones in several of the annual reports
on the mineral resources of the United
States, published by the United States
geological survey The quality of the
opals was thus described in the report
| for 1922
The best gem opal from this region
| is nnexcelled in variety and brilliance
OF fire and color by that from other
localities. The cut gems exhibit won
derful flashes of green, blue, yellow, and
red OF various shades. In some the
color is uniform over the whole stone or
over large areas, changing as the gem
is turned from green to red or from red
to blue, and so on. Some of the gems
show rich ultramarne blue in one
position with green or red in another.
Many gems display various bright colors
arranged in patches, and each patch
changes color as the stone is turned.
The brilliant flashes of peaeoek-fea
colors obtained from the opal of dark
color yields gem which might be called
black opal, but most OF it is not like
the Australian gem of that name, since
it occurs in thick pieces and the colors
are less localized. The majority of the
dark-colored gems, no matter how beau
tiful in reflected light, become a rich
reddish-brown color in transmitted
light. Lighter-colored opal with good
color and fire is also found and cuts
iffn varxy baanftf,,l 6,a,aa
The locality was visited by Douglas
b. SteTett for the geological survey,
August 10. 20 and 81. 1918, for the
purpose of procuring information for
the report on mineral resources for 1913
and for an enlarged report on precious
stones to be prepared during the course
Of the next three years.
0pals Found in Thinly Settled Regions.
The locality is in Virgin valley, in
northern Humboldt county. The nearest
postoffice or small town is DEMO, Greg, |
situated on the Nevada line. The opal !
field Is about IS miles southwest of |
DEMO and may be reached by automo |
bile or team from that town or from
Cedaryilley Calf. DEMO may be reached |
by stage, auto, or tea from Jungo or |
Winnemucca, New, distance of about |
So miles and 10 miles, respectively.
All the opal claims that have been |
located were not visited by Mr. Sterrett I
but several of those from which yalu-
able gem material has been obtained I
were examined. The occurrence of the
opal is similar at the different localities
The matrix consists of beds OF greenish
clay inclosing pebbles and debris OF
rhyolite and other rocks with varying
quantities of petrified wood. The opal
bearing clay beds are interbedded with
other strata of white, gray. and yellow
ish, more or less consolidated, mud,
sands, or grayels. These formations con
tain large proportion of volcanic ash
and breccia and are overlain by ba
saltic lava. The formations lie nearly
fiat or with dips rarely exceeding l0l
degrees. Block faulting has disturbed
the formations considerably SO that the
opal bearing strata occur at diverse ele
yations. The opal deposits examined lie
at elevations ranging from about 5000
to $500 feet above sea level Erosion
has exposed the formations in different
positions, SO that the opal strata out
'rop in places as bands in cliffs or steep
1illides or form blanket beds over small
areas under mesas and platcaus.
The opal.bearing clay is sticky and
gumbo-like when moist, but on drying
t swells and cracks apart to crum;
,ling mass Pick and shovel with horse
crapers are required for surface mining
md the former will probably answer all
purposes for underground mining.
fems Associated with Petrifed Wood.
The greater part of the precious opal
5 associated with petr6ed wood gen
rally forming cast of twigs, limbs,
ark, parts of tree trunks or roots or
occurring as seams or deposits in or
round petrified wood in which the orig
nal texture of the wood is beautifully
reserved.
A mistake has been made in cutting :
he Nevada opal too soon after il has (
cen mined. Time should be allowed for I
roper seasoning of the stone without I.
Exposure to dry air, so that any excess
( moisture may be lost slowly and !.
rithout causing the gems to crack.
The opal field has been very slightly Z
eveloped, but has probably yielded I
yer $4,000 worth of rough gems A |:
ew superb specimens worth several !:
undrcd dollars apiece and many fine (:
ems worth $50 to 5000 apiece have been ];
btained, and the prospects of the field !.
3 a producer of valuable opal are !:
RIGHT z