Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-10-09
TINE FORMATIONS WHICH ARE 0af-BfkR'
ING AND THOSE WHICH SEPARATE
THEM.

u. =. Geological survey Of II
Forsieth Parallel and the Personal
Research Of the Author.
Written for the Sentinel" by N. III. Joseph
Mineral Hill, which occupies the north
ern slope Of Prospect Mountain. is COM
posed OF dolomitic limestone and granite.
\ The Prospect Mountain qusrtzite. which
there dipping to the northeast, forms the
footwsll 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 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 ii underlies the
Prospect Mountain limestone east 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 n~ortherly 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 were
presumably one and the same and formed
. continuous body. The face OF the
qusrtzite dips under the limestone of the
Ruby Hill lode ct an average angle OF
about 40 degrees to the northeast. The
exposure OF this body Of limestone on the
surface extends over 4 900 linear feet from
near the Albion shaft on the northwest.
where 10 10 covered by the debris Of Spring
Valley 10 Q point southeast OF and beyond
the Jackson mine, where 10 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 10 cut of by 9 fault f%issure.
called the RUBY Hill fault" The width
OF the limestone zone Of Ruby Hill. ct the
surface. IL from 800 TO 1000 feet; over
lying IL on the north are the Secret Cam
yon shals and the Hamburg limestone of
Adams Hill. Overlying the quartzite.
10 q belt Of Hamburg limestone. which Ia
doubtless connected al some depth beneath
the surface with that OF Adams Hill. In
tervening those two bodies 81 the surface.
over Q space Of about 5000 feet. is the
Pogonip limestone, which run in Q con.
tinuous belt through the eastern portion
Of the district. from Diamond Valley,
north Of the Bullwhscksr mine TO Newark
Valley on the south. O~verlying the Ham.
burg limestone OF Prospect Mountain lisa.
band Of argilaceous shale identical In char.
acter with that which ~overlies the north.
srn part Of the Ruby Hill lode. but known
% the Hamburg shale. Nearly all Of
H ORE BODIES
OF considerable magnitude and economic
value that we're discovered In Eureka Dis
trict up 10 the present time were 10 the
Prospect Mountain and Hamburg lime
stone formations, Of the Cambrisn Age,
but valuable deposits Of ore have been
found in the Bullwhacker and Willisms-
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 qusrtzite
southwark to Newark Valley.
The shales and quartzites are substsn.
TALLY non. ore bearing. In some places
the Prospect Mountain qusrtzite In Ruby
Hill has been i~mpregnsted with the ore
bearing solutions, but 1t has nowhere been
found Of any economic value. Rhyolite.
. 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 solfataric action consequent upon it's
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
quartzite, on the east side Of Prospect
Mountain, is Q belt OF Secret Canyon shsle,
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 10 more
silicious than the former. and II weathers
rougher and breaks with Q sharper frac-
ture. Returning to the
RUB HILL FAULT.
II IL first observed northward. ct the sur
face near the Albion mine, taking an al
most uniform southessterly course, with
average dip. underground, OF about 10
degrees TO the northeast. It passes near
the Richmond Office and is plainly visible
near the mouth Of Q tunnel that was for
merly run TO connect with the Bell shaft;
northeast Of the Eureka and
& K shafts 10 q point between the Phenix
md Jackson mines, where 10 bends around