Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1897-08-14
Eureka District.
DEEPLEVEl MINING
The Ruby Hill Fault FissuTe.
ITS EXTENSION SOUTHWARK AND IN
fLueNcE UPON THE 0RE-BEARINc
STRUCTURE OF RUBY HILL AND
PROSPECT MOUNTAIN.
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.
rHf FORMATIONS WHICH ARE 0RF-BfAa'
ING AND THOSE WHICH SEPARATE
THEM,
Aaduced From the Records OF the
u. n. Geological survey of the
fortieth Parallel aud the Personal
Resenrch of the Author.

Resenreh of the Author.
,W,iueu for ne "Senfinel By N. II. Joseph
Mineral Hill, which occupies the north
arm slope Of Prospect Mountain, Is com
posed OF dolomitio limestone and granite.
!. The Prospect Mountain quArtzite. which
there dipping 10 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 a 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 ID 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 Dog Out mine. On the east flank
oi Prospect Mountain the quartzito dips
10 The east. The granite. which owes lite
exposure on the northerly slope OF Pros
psot Mountain TO erosion, apparently dips
under the auarizite 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 we're
presumably one aud the came and formed
a continuous body. The face OF the
quAr,zite dips under tho limestone OF the
Ruby Hill lode at an average angle OF
about 40 degrees 10 the northeast. The
exposure Of this body OF limestone on the
surface extends over 4. 600 linear feet from
near the Albion shaft on the northwest,
where 10 IA covered by the debris OF Spring
Valley 20 point southeast OF and beyond
the Jackson mine, where ID comes TO q mar
row point or wedge between the Prospect
Mountain quartziie and Pogonip lime
stone. On the northern end OF Ruby Hill
the limestone is cut off by fault fssure,
called the RUBY Hill fault" The width
OF the limestone zone OF Ruby Hill, ct the
surface. is from 800 to 1000 feet; over
lying ID on the north are the Secret Can.
yon shale and the Hamburg limestone Of
Adams Hill. 0yerlyiug the qusrtzite.
upon the east side OF Prospect Mountain,
10 q bslt OF Hamburg limestone, which Ia
doubtless connected at soms depth beneath
the surface with that OF Adams Hill. In
tervening those two bodies at the surface.
over . space OF about 5000 feet. ia the
Pogonip limestone. which runs in q con.
tinuous belt through the eastern portion
Of the district. from Diamond Valley,
north OF the Bullwhaeker mine TO Newark
Valley ON the south. overlying the Ham
burg limestone OF Prospect Mountain is q
band OF argilaoeous shale identical In char.
aeter with that which overlies the north.
ern part OF the Ruby Hill lode. but known
"a the Hamburg shale. Nearly all OF
THE ORE BODIES
vi considerable magnitude and economic
value that were discovered in Eureka Dis
triet up TO the present time were in the
Prospect Mountain and Hamburg lime
atone formations. OF the Csmbrian Age,
ous valuable deposits OF ore have been
tound in the Bullwhacker and Willisms-
oufs mines. which are In the Pogonip
,Imes'ons and quartz porphyry OF the 81
,ufiah Age. Very rich ore has been found
~ paying deposits In the mines OF New
iofk canyon, in Lone Mountain lime
s.one' also OF the Silurian Age. The Lone
Mouhtstn limestone Is separated from the
fogonip limestone by the hard quartzite
reei OF McCoy's Ridge. This qusrtzite
extends northward to Cariboo Hill and
sonthward to Newark Valley.
Ihe shales and quartzites are substsn.
.iaiiy non-ore. bearing. In some places
tne Prnspeet Mountain quartzite In Ruby
NH hts been impregnAted with the ore
oesring solutions, but II has nowhere been
ionnd OF any economic value. Rhyolite
: species OF the porphyry class of rocks
ignsous and non-ore. bearing, is found in
dykes OF various dimensions 10 several
parts Of the district and frequently in d.
rect touch with the ore bearing strata
The soifstarfc action consequent upon its
eruption had probably much to do with
the ascending e.bearing solutions, IL not
with the actual deposition of the ore.
Irending southerly from the end of tht
quartzite. on the east side OF Prospec
mountain, Is belt Of Secret Canyon shale
which separates the Hamburg limeston,
from the Prospect Mountain limestone
tnrougho ut the southern section OF ths
district. The Prospect Mountain and
hambur limestones are identical in char
aoter 10, all but thar the latter is NOR,
siiicionS than the former. and it weatheri
foughsr and breaks with sharper frac
ture. Returning to the
RUBY HILL FAULT.
~ 10 hrst observed nor rthwsrd, al the sur.
iacs rear the Albion mine. taxing an d.