Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-10-16
TINE foRMATIoHs WHICH ARE 0Rf.BEAR'
ING AND THOSE WHICH SEPARATE
THEM.
Adduced From the Records OF the
u. 9. Geological survey OF fhe
Fortfeth Parallel and the Personal
Research Of the Author.

OIL the Aush1OEs
/ Written for the "Sentinsl" BY N. III. Joseph.l
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
footwall Of the Ruby Hill lode. overiies
the granite and bends around Prospect
Mountain to the east and west in the form
of q horseshoe, trending on the east SIDE
to a point northeast Of and near the Eu-
reks Tunnel and on the west side to an
other point extended westward from the
Graut 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 dips
to the east. The granite, which owes its
on the northerly slope Of Pros.
pect Mountain to erosion, apparently dips
under the qusrtzite OF Buby Hill. Pre-
vious to the erosion, she great belt OF m
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
qusrtzits 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 10 10 covered by the debris Of Spring
Valley 10 o point southeast Of and beyond
the Jackson mine. where 10 comes to a mar.
row point or wedge between the Prospect
Mountain quartzite and Pogonip lime
stone. On the northern end of Ruby Hill
the limestone lie cut off BY q fsult assure,
called the Ruby Hill fault" The width
Of the limestone zone Of Ruby Hill, 81 the
surface. Ia from 800 to 1000 feet; over
lying II on the north are the Secret Gam
yon shale and the Hamburg limestone OF
Adams Hill. Overlying the quartzite,
upon ahs east side OF Prospect Mountain,
10 belt Of Hamburg limestone, which 10
doubtless connected at some depth beneath
the surface with that Of Adams Hill. In
tervsning those two bodies al the surface,
over q space OF about 5000 feet. IL 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 10 Newark
Valley on the south. Overlying the Ham,
burg limestone Of Prospect Mountain is .
band OF argilsceous shsle identical In char.
acter with that which o~verlies the north.
ern part OF the Ruby Hill lode. bat known
O. the Hamburg shale. Nearly all Of
THE ORE BODIES
OF considerable magnitude and economic
value that were discovered In Eureka Dis
trict up 10 the present time were 10 the
Prospect Mountain aud Hamburg lime
stone formations, Of the Csmbrian 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 IL separated from the
Pogonip limestone by the hard quartzite
reef OF McCoy's Ridge. This qusrtzite
extends northward to Oariboo Hill and
southwark to Newark Valley.
The shales and quartzites are substsn- |
TALLY bearing. In some places |
the Prospect Mountain quartzite in Ruby
Hill has been i~mpreRnated with the ore |
bearing solutions, but II has nowhere been |
Of any economic value. Rhyolits, |
Q species OF the porphyry class OF rocks,
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-besring solutions, IL not
the actual deposition OF the ore.
Trending southerly from the end of the
luartzite, on the east side Of Prospect
Is q belt Of Secret Canyon shale,
separates the Hamburg limestone
rom the Prospect Mountain limestone
the southern section Of the
The Prospects Mountain and
Hamburg limestones are identical In char
in all but that the latter 10 more
~ilicious than the former. and IL weathers
and breaks with q sharper frac-
Returning TO the
RUBY HILL III
q IL first observed northwsrd, al the sur
ace near the Albion mine, taking an al
most uniform southeasterly course, with
n average dip. underground, OF about 10
TO the northeast. 1t passes near
be Richmond Office and is plainly visible
Iesr the mouth Of tunnel that was for
nerIy run TO connect with the Bell shaft;
hence northeast Of the Eureka and
I x shafts 10 . point between the Phenix
: 4 r.-I.-- 49,. -kn.~ a. Ax~l~ $1,000