Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-11-06
Eureka District.
DEEPLEVEL MINING
The Ruby Hill Fault FissuTe.
ITS EXTENSION SOUTHWARK. AND IN
FlusacE UPON The oRE-sEARINc
STRUCTURE OF RUBY HILL 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 as Depth is AttaIned--
The Proportion Of Gold Increasing.
TINE fsRMATIeHs WHICH ARE 0Rf-SfAs-
ING AND THOSE WHICH SEPARATE
TINE fsRMA TIaHs WHICH ARE 0Rf-5fAH'
ING AND THOSE WHICH SEPARATE
THEM.
From the Records OF the
u. n. Geological survey OF she
Fortfetb Parallel and the Personal
Research Of the Author.


/ Written for the Sentinel by NJ. H.. Josephl
Mineral Hill, which occupies the north
ern slope of Prospect Mountain, is CON-
posed OF dolomitic limestone and granite.
y The Prospect Mountain qusrtzite. which
there dipping to the northeast, forms the
footwall of the Ruby Hill lode, o~verlies
the granite and bends around Prospect
Mountain to the cas-, and west in the form
of a horseshoe, trending on the east side
to a point northeast OF and near the Ed
reka Tunnel and on the west side to an
other point extended westward from The
Grant mine. There il sinks beneath the
surface debris, but again appears above
the mountain quarternarv Just southwest
OF and near the Prospect Mountain Tun-
mel, and still further south il underiies the
Prospect n tain limestone east OF aud
near the Dug Out mine. On the east hsnk
OF Prospect Mountain the quartzite dips
to the east. The granite, which owes its
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 were
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 30 the northeast. The
exposure OF this body Of limestone on the
surface extends over A, 900 linear feet from
nesr 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 il comes to a mar
row point or wedge between the Prospect
Mountain qnartzite and Pogonip lime
stone. On the northern end of Ruby Hill
she limestone ia cot off by a fault f~issrre,
called the "Ruby Hill ~fsnlt." The width
OF the limestone zone OF Ruby Hill. at the
surface, Is from 800 to 1000 feet; over
lying 10 on the north are the Secret Cam
yon shale and the Hamburg limestone OF
Adams Hill. OverIying the qusrtzite,
upon the east side Of Prospect Mountain,
IL a belt Of Hamburg limestone. which is
doubtless connected al 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 runs in a CON-
tinuous bslt through the eastern portion
OF the district. from Diamond Valley,
north Of the B~uliwhacker mine to Newark
Valley on the south. Oyerlying the Ham
burg limestone Of Prospect Mountain is q
band OF argilaceous shale identical in CHAR
acter with that which ~overlies the north
ern part OF the Ruby Hill lode. but known
as the Hamburg shale. Nearly all Of
THE ORE BODIES
OF considerable magnitude aod 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 Cambrisn Age,
but valuable deposits Of ore have been
found in the Bullwhscker aud Williams-
burg mines. which are in the Pogonip
limestone and quartz porphyry OF the ST.
luriau Age. Very rich ore has been found
10 paying deposits b 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 Mcooy's Ridge. This quartzite
extends %northward to Csriboo Hill and
southwark to Newark Valley.
The shales and quantities. 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 1t has nowhere been
found OF any economic value. Rhyolite,
q species of the porphyry class Of rocks,
lku6Oud duQ Ou-Of DCoIAbS ~ AOouQ III
dykes OF various dimensions in several
parts OF the district and frequently in di-
rect touch with the ore bearing strata.
The solfataric 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.
Trsnding southerly FROM the end Of the
quartzite, 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 ii weathers
rougher and breaks with q sharper frac-
ture. Returning TO the
RUBY HILL FAULT.
II ia first observed northward. 81 the sur
face near the Albion mine, taking an al
most uniform sontheasterly course, with
an average dip. underground, OF about 10
degrees TO the northeast. 1t passes near
the Richmond Office and lie plainly visible
near the mouth Of a tunnel that was for
merly run TO connect with the Bell shaft;
thence northeast OF the Eureka and
K K shafts TO q point between the Phenix
And Iaakaon ufnea. where IA bends around