Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-09-04
Eureka District.
DEEPLEVEL MINING
The Ruby Hill Fault Fissure.
ITS EXTENSION SOUTHWARK AND IN
rLUENcs UPON THE 0RE-BEARISc
STRUCTURE OF RUBY MILL AND
PROSPECT MOUNTAIN.
Ore Still Going Down Below the Lowest
Workings Of the Eureka Con. Mine
improvement in Quantity and Quality
Of the Ore in the Diamond and Excel
siOr Mines az Depth is ittained--
The Proportion Of Gold Increasing.
TINE fosMITIeEs WHICH ARE 0RE.BfAa-
ING AND THOSE WHICH SEPARATE
THEM.
From the Records OF n
u. y. Geological survey OF n
rorttetb Parallel and the Personal
Research of the Author.

Hr1Ien IoT ht .ScHtthct " ~NI"I
Mineral Hill, which occupies the north
ern slope of Prospect Mountain, Is com
posed OF dolomitic Limestone and granite.
. The Prospect Mountain quartzite, which
there dipping TO the northeast, forms the
iootwsll Of the Ruby Hill lode, overlies
the granite and bends around Prospect
Mountain to the east and west in the form
OF q horseshoe, trending on the east side
to q 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 ID sinks beneath the
surface debris, but again appears above
the mountain qusrternary just southwest
OF and near the Prospect Mountain Tun-
mel, and still further south il underlies the
Prospect Mountain limestone cas-. of and
near the Dug Out mine. On the east flank
Of Prospect Mountain the quartzite dips
to the east. The granite, which owes its
exposure on the northerly slope Of Pros
poet Mountain to erosion, apparently dips
under the qusrtzite 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 we're
presumably one and the same and formed
q 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 10 9 point southeast Of and beyond
the Jackson mine, where il comes to a mar
row point or wedge between the Prospect
Mountain qusrtzite 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 1t on the north are the Secret Csn-
yon shsle and the Hamburg limestone Of
Adams Hill. O~verlying the quartzite.
upon the east side Of Prospect Mountain,
10 q 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 . space OF about 5000 feet, ia the
Pogonip limestone, which runs in q CON-
tinuous belt through the eastern portion
Of the district. from Diamond Valley,
north OF the Bullwhacker mine to Newark
Valley on the south. Overlying the Ham,
burg limestone OF Prospect Mountain is q
band OF argilaceous shale identical In char
acter with that which o~verlies the north.
ern part OF the Ruby Hill lode, but known
% the Hamburg shale. Nearly all Of
THE ORE BODIES
OF considerable magnitude and economic
value that were discovered in Eureka Dis
trict up 70 the present time were in the
Prospect Mountain and Hamburg lime
stone formations, OF the CambriAn Age,
but valuable deposits OF ore have been
found in the Bullwhscker 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 the hard quartzite
reef Of McCoy's Ridge. This quartzi.e
extends northward to Cariboo Hill and
southwark to Newark Valley.
The shales and qusrtzites are substan-
TALLY non-ore-bearing. In some places
the Prospect Mountain quartzite in Ruby
Hill has been impregnsted with the ore
bearing solutions. but 1t has nowhere been
found Of any economic value. Rhyolite,
Q species Of the porphyry GLASS 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 solfstaric action consequent upon it's
eruption had probably much to do with
the ascending ore bearing solutions, IL not
with the actual deposition of the ore.
Trending southerly from the end of the
qusrtzite, on the east side Of Prospect
Mountain, is q belt Of Secret Canyon shale,
which separates the Hamburg limestone
from the Prospect Mountain limestone
throughout the southern section OF the
district. The Prospect Mountain and
Hamburg limestones are identical in char
acter in all but that the latter is more
silicious than the former. and 1t weatners
rougher and breaks with q sharper frac-
ture. Returning to the
RUB HILL FAULT.
II IL first observed northward. at the sur
face near the Albion mine, taking an al
most uniform southeasterly course, with
an average dip. underground, Of about 10
degrees TO the northeast. II passes near
the Richmond Office and Ia plainly visible
near the mouth Of Q tunnel that Was for
merry run to connect with the Bell shaft;
thence northeast Of the Eureka and
z K shafts to 9 point between the Phenix
md jackson mines, where II bends around