Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-09-11
TINE FORMATIONS WHICH ARE oRE-BfAR'
ING AND THOSE WHICH SEPARATE
THEM.
Adduced From the Records OF Ia
u. 3. Geological survey OF n
Fortfeth Parallel and the Personal
Research of the Author.

Written for he Sentinel" by M. III. Joseph.l
Mineral Hill, which occupies the north
ern slope OF Prospect Mountain, is COM
posed OF dolomitic limestone and granite.
y The Prospect Mountain quartzi.e. 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 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
Grant mine. There il sinks beneath the
surface debris, but again appears above
the mountain quarternsry just southwest
of and near the Prospect Mountain Tun-
mel, and still further south it 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 northerly slope Of Pros
pect Mountain to erosion, apparently dips
under the quartzite 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
. OO0y NV law Va ~
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 4 1000 linear feet from
near the Albion shaft on the northwest,
where ID 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 qusrtzite and Pogonip lime
stone. On the northern end Of Ruby Hill
the limestone ia cut off by a fault f~issure,
called the "Ruby Hill fsult." The width
Of the limestone zone Of Ruby Hill. ct the
surface, is from 800 to 1000 feet; over
lying it on the north are the Secret Can
yon shale and the Hamburg limestone Of
Adams Hill. 0verlying the quartzite,
upon the east side Of Prospect Mountain,
10 . belt Of Hamburg limestone. which ia
doubtless connected al some depth beneath
The surface with that Of Adams Hill. In
tervening those two bodies at the surface,
over 9 space OF about 5000 feet, is the
Pogonip limestone, which runs In a con-
tinuous belt through the eastern portion
Of the district. from Diamond Valley,
north Of the Bullwhacker mine to Newark
Valley on The south. O~verlying the Ham
burg limestone Of Prospect Mountain Ia q
band OF argilaceous shale identical In char.
acter with that which overlies 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 we're discovered in Eureka Dis
triot up TO the present time were in the
Prospect Mountain and Hamburg lime
stone formations, OF the Csmbrian Age,
but valuable deposits of ore have been
found in the Bullwhacker 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 qusrtzite
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 im~pregnated with the ore
bearing solutions, but II has nowhere been
found Of any economic value. Rhyolite,
. species of the porphyry class OF rocks,
and bearing, ia found in
dykes Of various dimensions in several
parts Of the district and frequently in d.
rect touch with the ore bearing strata.
The solfstaric action consequent upon its
had probably much to do with
the ascending ORE bearing solutions, II not
the actual deposition Of the ore.
Trending southerly from the end OF the
uuartzite, on the east side Of Prospect
IL . belt Of Secret Canyon shale,
separates the Hamburg limestone
rom the Prospect Mountain limestone
the southern section OF the
district. The Prospects Mountain and
Hamburg limestones are identical In char
lcter 10 all but that the latter is more
~tilicious than the former. and il weathers
and breaks with q sharper frac-
Returning 10 the
RUBY Hill FAULT.
u IL fret observed n~orthward, 81 the sur
ace near the Albion mine, taking an al
most uniform southessterly course, with
% average dip. underground, OF about 20
lsgrees to the northeast. 1t passes near
he Richmond Office and is plainly visible
ear the mouth Of q tunnel that was for
nerly run to connect with the Bell shaft:
hence northeast Of the Eureka and
, K shafts 70 9 point between the Phenix
I'd Jsetson mines, where u bends around