Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-09-25
Eureka District.
DEEPLEVEL MINING
The Ruby Hill Fault FissuTe.
ITS EXTENSION SOUTHWARK AND IN
FLuEHcs UPON the 0RE-BEARISc
STRUCTURE OF RUBY HILL AND
PROSPECT MOUNTAIN.
Ore Still Going Down Below the Lowest
Workings of the Eureka Con. Nine
Improvement in Quantity and Quality
of the Ore in the Diamond and Excel
sior Mines as Depth is Attained--
The Proportion Of Gold Increasing.
THE FORMATIONS WHICH ARE 02E.8fAa-
ING AND THOSE WHICH SEPARATE
THEM.
THE FORMATIONS WHICH ARE o4t.sfAa-
ING AND THOSE WHICH SEPARATE
THEM.
From the Records of the
IT,. y. Geological Survey of h
rortfeth Parallel aud the Personal
Research OF the Author.


rortfeth Parallel aud the Personal
Research OF In Author.
/ Written for tie Sentinel By NJ. II. Joseph.l
Mineral Hill, which occupies the north
ern slope Of Prospect Mountain, Is COM
posed OF dolomitic limestone and granite.
y The Prospect Mountain quartzite. which
there dipping to the northeast, forms the
footwall of the Ruby Hill lode. overlies
the granite and bends around Prospect
Mountain to the east and west in the form
OF a horseshoe, ~trending on the east side
to a point northeast OF and near the Eu-
reka Tunnel and on the west side to an
other point extended westward from The
Grant mine. There ii sinks beneath the
surface debris, Blu again appears above
the mountain quarternary just southwest
of aud near the Prospect Mountain Tun-
mel, and still further south ID underlies the
Prospect q tain limestone east of and
near the Dug Out mine. On the east flank
OF Prospect Mountain the quartzi.e dips
to the east. The granite, which owes it's
exposure on the northerly slope OF Pros.
poet Mountain to erosion, apparently dips
under the quartzite OF Ruby Hill. Pre-
vious to the erosion, the great belt of lime
stone of Prospect Mountain and that
which constitutes the Ruby Hill lode were
presumably one and the same and formed
o continuous body. The face OF the
quartzite dips under the limestone OF the
Ruby Hill lode at an average angle OF
about 40 degrees to the northeast. The
exposure Of this body of limestone on the
surface extends over 1000 linear feet from
near the Albion shaft on the northwest,
where ID 10 covered by the debris Of Spring
Valley TO q point southeast of and beyond
the Jackson mine, where ID comes TO q mar
row point or wedge between the Prospect
Mountain quartzite and Pogonip lime
stone. On the northern end of Ruby Hill
the limestone is cut off by q fault ~fissure,
called the "Ruby Hill fault" The width
OF the limestone zone Of Ruby Hill. at the
surface, is from 800 to 1000 feet; over
lying Ii on the north are the Secret Cam
yon shale and the Hamburg limestone of
Adams Hill. Everything the qusrtzite.
upon the east side Of Prospect Mountain,
ia a belt Of Hamburg limestone, which is
doubtless connected at some depth beneath
the surface with that OF Adams Hill. In
tervening those two bodies at the surface.
over Q space Of about 5000 feet, is the
Pogonip limestone, which rum in a CON-
tinuous belt through the eastern portion
Va tu6 uistIicsb AIOm DtbuiOuQ fhlioys
north OF the BullwhAcker mine to Newark
Valley on the south. Overlying the Ham
burg limestone OF Prospect Mountain is q
band Of argilsceous shale identical in CHAR
aoter with that which o~verlies the north
ern part Of the Ruby Hill lode. but known
as the Hamburg shale. Nearly all OF
Il ORE BODIES
OF considerable magnitude and economic
-xI-a kLAA h. lovA.% l.. E--zl~ III
trict up to the present time were in the
Prospect Mountain and Hamburg lime
stone formations, Of the Cambrisn Age,
but valuable deposits Of ore have been
found in the Bullwhacker and Williams
burg mines. which are in the Pogonip
limestone and quartz porphyry OF the ST.
lurian Age. Very rich ore has been found
in paying deposits In the mines OF New
York Canyon, In Lone Mountain lime
stone, also OF the Silurian Age. The Lone
Mountain limestone is separated from the
Pogonip limestone by she hard quartzite
reef Of McCoy's Ridge. This quartzite
extends northward to Csriboo Hill and
southwark to Newark Valley.
The shalss and quartzites are substan-
TALLY non-ore-bearing. In some places
the Prospect Mountain quartzite in Ruby
Hill has been i~mpregnated with the ore
bearing solutions, but ii has nowhere been
found Of any economic value. Rhyolite.
q species Of the porphyry class Of rocks.
igneous and non-ore- bearing, Is found in
dykes OF various dimensions in several
parts Of the district and frequently in di-
rect touch with the ore bearing strata.
The solfstsric action consequent upon its
eruption had probably much to do with
the ascending ore-besring solutions, il not
with the actual deposition Of the ore.
Trending southerly from the end of the
quartzite, on the east side Of Prospect
Mountain. is q belt OF Secret Canyon shsle,
which separates the Hamburg limestone
from the Prospect Mountain limestone
the southern section Of the
district. The Prospects Mountain and
Hamburg limestones are identical in char
aeter in all but that the latter is more
than the former. and il weathers
and breaks with q sharper frac-
ture. Returning to the
RUBY HILL AUL
II is first observed n~orthward, at the sur
face nee- the Albion mine, taking an al
most uniform southessterly course, with
IN average dip, underground, OF about 10
degrees TO the northeast. II passes near
The Richmond Office and is plainly visible
near the mouth OF q tunnel that was for
meriy run TO connect with the Bell shaft;
northeast OF the Eureka and
Z K shafts TO . point between the Phenix
md Jackson mines, where u bends around