Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-10-23
the FORMATIONS WHICH ARE 0af-BtAa'
ING AND THOSE WHICH SEPARATE
THEM.
Adduced From fhe Records OF u
u. ~. Geological survey of IN
Fortfeth Parallel and the Personal
Research OF the Author.

u ~. eeotOSte"t SURVEY
Fortieth Parallel and IA Personal
Research OF the Author.
Written for he "Sentinsl" by N. II. Joseph
Mineral Hill, which occupies the north
ern slope Of Prospect Mountain, 10 com
posed OF doiomitio limestone and granite.
= The Prospect Mountain quartzite. which
there dipping to she northeast, forms the
footwall Of the Ruby Hill lode. overlies
the granite and bends around Prospect
Mountain to the east and west in the form
of a horseshoe, trending on the east side
to a 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 qusrternary just southwest
of and near the Prospect Mountain Tun-
mel. and still further south il underlies the
Prospect tain limestone east Of and
near tbs Dug Out mine. On the east flank
OF Prospect Mountain the quartzite dips
to the east. The granite, which W its
exposure on the n~ortherly slope of Pros.
poet Mountain TO erosion, apparently dips
under the qusrtzite of Buby Hill. Pre-
vious to the erosion, the great belt OF lime
stone of Prospect Mountain and shat
which constitutes the Ruby Hill lode were
presumably one and the same and formed
a continuous body. The face OF the
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 1000 linear feet from
near the Albion shaft on the northwest.
where ID 10 covered by the debris Of Spring
Valley 10 q point southeast OF q beyond
the Jackson mine, where 10 comes to q mar
row point or wedge between the Prospect
Mountain quartzite and Pogonip lime
tone. On the northern end OF Ruby Hill
the limestone is cut off by a fault ~fssure,
called the ''Ruby Hill fault" The width
OF the limestone zone Of Ruby Hill, at the
surface, Ia from 800 to 1000 feet; over
lying II on the north are the Secret CAN
yon shale and the Hamburg limestone OF
Adams Hill. Overlying the quartzite,
upon the east aide Of Prospect Mountain,
10 a belt OF Hamburg limestone. which ia
doubtless connected al some depth beneath
the surface with that OF Adams Hill. In
terveniug those two bodies al the surface.
over q space OF about 5000 feet, IL the
Pogonip limestone, which RUM 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. Everything the Ham
burg limestone Of Prospect Mountain is a
band OF argilaoeous shsle identical In char.
scter with that which ~overlies the north.
ern part OF the Ruby Hill lode. but known
az the Hamburg shale. Nearly all OF
THE ORE BODIES
OF considerable magnitude and economic
value that we're discovered In Eureka Dis
trict up to the present time we're in the
Prospect Mountain and Hamburg line
stone formations, Of the Csmbrisn Age,
but valuable deposits OF ore have been
found in the B~ullwhscker 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 quartzite
extends northward to Csriboo Hill and
southwark to Newark Valley.
The shalss aud quantities. are substan-
TALLY non-ore-bearing. In some places
the Prospect Mountain quarszite in Ruby
Hill has been impregnated with the ore
bearing solutions, but it has nowhere been
found OF any economic value. Rhyolite,
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 solfstsric action consequent upon its
had probably much TO do with
the ascending ore bearing solutions, il not
with the actual deposition Of the ore.
Trending southerly from the end of the
quartzite, on the east side Of Prospect
is a belt OF Secret Canyon shale,
which separates the Hamburg limestone
from the Prospect Mountain limestone
the southern section OF the
The Prospect Mountain and
limestones are identical In char
sctsr in all but that the latter is moro
,~ilicious than the former. and IL weathers
rougher and breaks with a sharper frac-
Returning to the
RrBY HILL u
II is first observed northward, at the sur
lace near the Albion mine, taking an al
most uniform southeasterly course, with
10 average dip. underground, OF about 10
10 the northeast. II passes near
he Richmond Office and lie plainly visible
lear ths mouth OF q tunnel that was for
nerly run to connect with the Bell shaft;
hence northeast Of the Eureka and
( K shafts 10 q point between the Phenix
nd Jackson mines, where II bends around