Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-07-03
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.
THE FORMATIONS WHICH ARE 0Rf-BfAa
INC AND THOSE WHICH SEPARATE
THEM,
Adduced From the Records Of the
n. n. Geological survey of the
Fortieth Parallel ANA the PersoDai
Re.earch of the Author.

tWriasn for the Sentinel" BY N. ~. Joseph
Mineral Hill, which occupies the north
eru slope OF Prospect Mountain. is com
po.ed OF dolomitic limestone aud granite.
The Prospect Mountain quartzite, which
thsre dipping 20 the northeast, forms the
footwsll Of the Ruby HUI 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
10 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 quarternary just southwest
OF and near the Prospect Mountain Tun-
mel, and still further south IL underlies The
Prospect Mountain limestone east OF ana
near the Dug Out mine. On the east nank
OF Prospect Mountain the qusrtzise dips
to the east. The granite. which owes its
exposure on the northerly slope OF Pros
peot Mountain TO erosion. apparently dlpF
under the qusrtzite OF huby Hill. IRE
yious 10 the erosion, the great belt OF lime
stone OF Prospect Mountain and thaf
which constitutes the Ruby Hill lode we're
presumably one aud the same and formed
4 continuous body. The face OF the
ausrtzits 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 IL 10 covered by the debris OF Spring
Valley 20 point southeast OF and beyond
the Jackson mine, where ID comes to a mar
row point or wedge between the Prospeci
Mountain quartzite aud Pogonip lime
stone. On the northern end OF Ruby Hill
ths limestone is cut off by fault assure.
called the "Ruby Hill fault" The width
OF the limestone zone OF Ruby Hill. at the
surface. Is from 800 TO 2.000 feet; over
lying 10 on the north are the Secret Can.
yon shale aud the Hamburg limestone OF
Adams Hill. Overlying the quartzite.
upon the east side Of Prospect Mountain,
10 q belt OF Hamburg limestone. which is
doubtless connected at some depth beneath
the surface with that OF Adams Hill. In
tervening those two bodies a, the surface.
over . space OF abou. 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 10 Newark
Valley on the south. overlying the Ham
burg limestone OF Prospect Mountain is q
band OF argilaceous shaie identical IN char.
acter with that which overlies the north
ern part OF the Ruby Hill lode. but known
as the Hamburg shsle. Nearly all Of
THE ORE BODIES
OF considerable magnitude and economic
value that were discovered in Eureka Dis
triot up 10 the present time we're in the
Prospect Mountain aud Hamburg lime
stoue formations, OF the Cambrian Age,
ous valuable deposits Of ore have been
iouna In the Bullwhscker aud Williams
ourg mines. which are In the Pogonir
hmestons and quartz porphyry OF the ST.
iurian Age. Very rich ore has been found
In paying deposits In tbe mines OF Nes
York Canyon, in Lone Mountain lime
STONE, also OF the silurian Age. The Lone
Mountain limestone is separated from the
fogonio limestone by the hard ausrtzitt
reel OF McCoy's Ridge. This auartgit,
extends northwsrd to Cariboo Hill and
southward to Newark Valley.
The shales and quartzitss are substan
tiaiiy non-ore. bearing. In some places
tne prospect Mountain quartzite In RUBY
mn mas been impregnated with the ore
oearing solntions. but IL has nowhere beer
found OF any economic value. Rbvolite
species OF the porphyry class Of rocks
igneous and non.ore bearing, ia found ir
dykes OF various dimensions in sevsrs
parts Of the district and freonsn,lv in a;
rect touch with the oro bearing str.,s
The solfAtsric action copsequens upon ~
eruption had probably much to do viii
the ascending ore. bearing solutions. il no
with the actual deposition of the ore.
Trending southerly from the end OF ,b
quartzite, on the east side of Prosnec
Mountain. Ia belt OF Secret Canyon sbale
which separates the Hamburg limeston
from the Prospect Mountain limeston
throughout the southern section Of IN
district. The Prospect Mountain an,
Hamburg ltmestones are identical In char
ao.er In ALI but that the latter is NOR
siiicious than the former. and IL weather
Iougher and breaks with sharper frac
ture. Returning to the
RUBY HILL FAULT.
II 10 hrst observed northwsrd. Al Aha an,
lace near the Albion nina. tstirc :,