Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-08-28
Eureka District.
DEEPLEVEL MINING
The Ruby Hill Fault Fissure.
ITS EXTENSION SOUTHWARK AND IN
Flusscs UPON THE oaE-BEAaINc
STRUCTURE OF RUBY HILL AND
PROSPECT MOUNTAIN.
Ore Still Going Down Below the Lowest
Workings of the Eureka Con. Mlne--
Improvement In Quantity and Quality
of the Ore in the Diamond and Excel
sior Mines as Depth is Attaintd--
The Proportion Of Gold Increasing.
the FORMATIONS WHICH ARE 0RE-BfAR'
ING AND THOSE WHICH SEPARATE
THEM.

Aadueea From the Records of the
U. =. Geological survey of the
rorttetn Parallel aud the Personal
Research Of the Author.
Written for ne "Sentinel" BY N. II. JosspAl
Mineral Hill, which occupies the north
ern slope Of Prospect Mountain. ia com
posed Of dolomitic limestone and granite.
= The Prospects Mountain quartzite, when
there dipping to .he northeast, forms the
footwall Of the Ruby Hill lode. oyeriies
the granite aud bends around Prosper
Mountain to the east and west in the form
of a horseshoe, ~trending on the east SIDE
to q point northeast OF and near the Eu-
reks Tunnel and on the west side 70 an
other point extended westward from Inc
Grant mine. There il sinks beneath the
surface debris, but again appears above
the mountain quarternary just southwest
of and near the Prospect Mountain Tun-
mel, and still further south il underlies the
Prospect Mountain limestone east Of and
near the Dug Out mine. On the east flank
Of Prospect Mountain the quartzite dip
to the east. The granite, which owes It's
exposure on the northerly slope OF Pros
pect Mountain to erosion, apparently dips
under the qusrtzite Of Ruby Hill. Pre-
yious 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
qusrtzite 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 1900 linear feet from
near the Albion shaft on the northwest,
where ID il covered by the debris OF Spring
Valley 70 3 point southeast OF and beyond
the Jackson mine, where ID comes to g 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 1900 feet; over
lying II on the north are the Secret Can
yon shale and the Hamburg limestone Of
Adams Hill. Overlying the qusrtzite.
upon the east side Of Prospect Mountain,
10 q belt Of Hamburg limestone. which 10
doubtless connected at some depth beneath
the surface with that OF Adams Hill. In
teryening those two bodies ct the surface,
over q space OF about 5000 feet, is 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 argiiaceous shsle identical in char.
acter with that which o~verlies the north
srn part OF the Ruby Hill lode. but known
-. u.-L..n NAaxIg all NJ
THE ORE BODIES
OF considerable magnitude and economic
value that were discovered in Eureka Dis
trict up TO 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 81
lurian Age. Very rich ore has been found
Ia 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 quartzite
extends northwsrd to Cariboo Hill and
southwark TO Newark Valley.
The shales and quartzites are substsn-
TALLY non-ore-bearing. In some places
the Prospect Mountain quarszite in Ruby
Hill has been impregnated 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 solfatsric action consequent upon its
eruption had probably much TO do with
the ascending ore-bearing solutions, ii not
with the actual deposition OF the ore.
Trending southerly from the end OF the
ouartzite, on the east side Of Prospect
Mountain, is q belt Of Secret Canyon shale.
which separates the Ham burg limestone
from the Prospect Mountain limestone
throughout the southern section OF the
district. The Prospects Mountain and
Hamburg limestones are identical In char
acter in all but that the latter Is more
silicious than the former, and ii weathers
roueher and breaks with q sharper frao-
ture. Returning to the
RUBY HILL III
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 sbout 70
degrees 70 the northeast. II passes near
the Richmond Office and lie plainly visible
near the mouth OF q tunnel that was for
merly run TO connect with the Bell shaft;
thence northeast OF the Eureka and
K K shafts 70 Q point between the Phenix
and Jackson mines, where 10 bends around