Geology and Drill Targets
North Springs gold prospect
Mineral Ridge Mining District, Esmeralda County, Nevada
for
Tonogold Resources, Inc.
La Jolla, California
by
Donald G. Strachan, Geologist, MSc. CPG
Gardnerville, Nevada
April 2005
Abstract
Geologic potential of Tonogold’s North Spring gold prospect may be comparable
to the northeast flank of Mineral Ridge, which produced 602,000 ounces of gold through
2002. Steep intrusive-sedimentary contacts and the steeper limbs of folds on the
northeast flank of Mineral Ridge are favored locations for larger tonnages and better
grades of “Main Stage” gold-bearing quartz lenses. At the North Spring gold prospect,
on the southwest flank of Mineral Ridge, the mineralized intrusive-sedimentary contact
may steepen beneath thin Tertiary cover west and southwest of the Roadrunner workings
and beneath Quaternary alluvium southwest of the Coyote Summit workings. Both
covered areas are adjacent to gold-mineralized outcrops and should be explored by
drilling.
Gold values on the North Springs property exceed 0.80 opt Au in at least one grab
sample from the Roadrunner workings, an area of silicified shears in and near the granitegneiss-schist contact, a small-scale duplicate of the Mineral Ridge’s “Main Stage” gold
mineralization. Host rock for gold at the Roadrunner prospect is quartz-veined and
silicified phyllitic siltstone, and alaskite and granite pegmatite apophyses. The enclosing
limestones and phyllites of the Wyman Formation are gently folded around near-vertical,
west-striking axial planes.
Alteration of Wyman phyllite ranges from proximal silicic at the Roadrunner
workings to distal propylitic 1,000 feet west, in a stream bed at the edge of the preTertiary outcrop. The propylitic phyllite at this location is cut by banded sugary quartz
veinlets, the most prominent striking N40ºE and dipping 90º. The Roadrunner gold
mineralization is confined to a gently dipping, undulating, but planar sheared contact
between high-level differentiates (alaskite, pegmatite) of the Mineral Ridge pluton and
Wyman phyllites and limestone. Undulations in the contact zone seem to follow broad
folds developed in the Wyman sediments. Steep limbs of similar folds were always
underground development targets for mine operators on the northeast side of Mineral
Ridge. These same methods should be applicable to exploration at Roadrunner:
extensions of the mineralized “Sts” horizon could be followed with a patterned drilling
program to explore the pluton-sedimentary contact as it steepens under post-mineral
cover.
The Coyote Summit prospect occurs in granite, granite gneiss, alaskite, and
pegmatite with numerous zenoliths of Wyman limestone and phyllites. Intrusive textures
and abundance of Wyman zenoliths suggests the Coyote Summit mineralization was
proximal to the now-eroded intrusive-sedimentary contact. Local foliation patterns and
district-scale lithologic geometry suggest the intrusive-sedimentary contact is steepening
and may be preserved beneath alluvium southwest of the Coyote Summit workings.
Do test the full potential of North Springs, the prospect should first be surveyed
by ground magnetics, resistivity and perhaps CSAMT, then drilled with a minimum of 10
holes for a total of about 4,000 feet.
Table of Contents
Abstract
2
Introduction
4
Geology of the Mineral Ridge District
5
Prospect Geology
8
Discussion
10
Conclusions
10
Recommendations
11
References
11
Illustrations
Plate
1
Location map, Mineral Ridge Mining District
Appendix
Plate
3
Geologic map, Mineral Ridge District
Appendix
Plate
4a
Claim block and location map, North Springs property
Appendix
Plate
4b
Geologic map, North Springs property
Appendix
Plate 5
Geologic sections locating potential gold zone, N. Springs
Appendix
Plate
Geologic map, Roadrunner prospect, North Springs
Appendix
Geologic map, Coyote Summit prospect, North Springs
Appendix
6a
Plate 7a
Introduction
Purpose
Tonogold Resources, Inc., (Tonogold) acquired the North Springs property as a
possible unmined analogy of the gold deposits on the northeast side of Mineral Ridge.
This report examines geologic and geochemical data from published and other sources to
provide understanding of geologic potential towards Tonogold’s decision.
Property description, access, and ownership
The North Spring claims are located 11 miles by road west of the town of Silver
Peak on the southwest side of Mineral Ridge in the Silver Peak Range, Esmeralda
County, Nevada (Plate 3). As of this report, a total of 120 lode claims are located in
sections 28, 29, 32 & 33 Township 1 South, Range 38 East and sections 4 & 5, Township
2 South, Range 38 East. Sixteen of these claims, NS-1 through 8, and CS-1 through 8,
were located by Mountain Gold Exploration, Inc (MGEI) of Carson City, Nevada. The
remaining 104 NSP claims were staked in September, 2004, by Tonogold after leasing
the original 16 claims (Davis, 2004). Only 38 of the original 120 claims should be
retained, but an additional 16 new claims should be staked (see “Recommendations”
below).
Property history
Shallow prospect pits and several shafts (both inclined and vertical) on quartz
veins may extend as deep as 75 feet on the Roadrunner prospect. Shallow workings are
also evident at the Coyote Summit prospect (Plate 4a). These workings may date from
the early 1900’s through the 1970’s.
Modern gold exploration began when Golden Phoenix Minerals, Inc., staked the
area in 2000. MGEI located the original “NS” (Roadrunner area) and “CS” (Coyote
Summit area) claims after the area came open in 2002. Tonogold leased MGEI’s claims
in September, 2004. Field mapping for this report was carried out in March, 2005.
Tonogold geochemistry
Tonogold took 24 samples at Roadrunner and Coyote Summit prospects in
September, 2004. Gold and silver assays of these samples are shown in Table 1.
Geophysics
Property-scale geophysics specific to the North Springs property are not available.
Drilling
No drill hole information are known for the North Springs property.
Geology of the Mineral Ridge District
The original Silver Peak District has been divided into two districts based on
differences in economic geology: the Red Mountain and Mineral Ridge districts. In the
Red Mountain District, silver was produced from mid-Pliocene veins in Tertiary volcanic
rocks (Nivloc, Mohawk, and Sixteen-to-One mines). The Nivloc (discovered in 1907)
operated from 1937 to 1943 at a grade of 11.0 opt Ag and 0.05 opt Au. The Mohawk
(1920) produced during the 1950’s at an average grades of 22.5 opt Ag (Albers &
Stewart, 1972, page 71). The Sixteen-to-One produced 1 million tons grading 8.0 opt Ag
and variable gold from 1982 (Brown, 2003, page 37) to approximately 1985.
Mineral Ridge produced 629,000 ounces gold from quartz veins, masses, and
disseminations through the 1930’s, mostly from the Mary and Drinkwater deposits.
Golden Phoenix’s open-pittable gold resource at Mineral Ridge Mine stands at 551, 245
ounces (Brown, 2003, page 82). The underground strike and dip potential of the Mineral
Ridge deposits are unknown. The geology of Mineral Ridge, including Tonogold’s North
Springs prospect to the west, is discussed in more detail below.
Stratigraphy of Mineral Ridge and Rhyolite Ridge
Paleozoic sediments
Precambrian, Cambrian, and Ordovician sediments outcrop on the flanks of
Mineral Ridge and the crest extending to the northwest (Plate 3). The Precambrian
Wyman Formation (map symbol: “wy”) is the oldest and most extensively preserved unit
in the district, outcropping on both flanks and over the crest of Mineral Ridge. The
Wyman Formation consists of several thousand stratigraphic feet of grey and dark
greenish grey phyllitic siltstone and phyllitic claystone with minor limestone, limey
siltstone, and limey sandstone. The Precambrian Reed Dolomite (“er”) is common on the
northeast and east flanks of Mineral Ridge, and may consist of as much as 1,500
stratigraphic feet of gray to yellowish brown crystalline dolomite. The Deep Spring
Formation (“ds”), youngest of the Precambrian units, occurs on the crest and
southwestern flank of Mineral Ridge and amounts to as much as 1,500 stratigraphic feet
of grey, finely crystalline limestone and dolomite.
Cambrian strata in the Mineral Ridge District include the Campito, Poleta,
Harkless, Mule Spring, and Emigrant formations. Several thousand feet of Precambrian
and Cambrian phyllitic siltstone of the Campito Formation (“Cca” and “Ccm”) outcrops
low on both flanks of Mineral Ridge and to the northwest. Almost 2,000 feet of Lower
Cambrian limestone and siltstone of the Poleta Formation (“Cp”) also outcrops low on
the flanks of Mineral Ridge, followed by 3,500 feet of the Lower Cambrian Harkless
siltstone (“Ch”) and 500 feet of the Lower Cambrian Mule Springs Limestone (“Cms”).
Ordovician Palmetto siltstone outcrops in two places on the northwest extension of
Mineral Ridge (Albers & Stewart, 1972, pages 5 to 18 and Plate 1). All Paleozoic
stratigraphic units are regionally metamorphosed, folded, and faulted as described below.
Tertiary strata
Pliocene volcanics and volcaniclastics outcrop along the southern and northern
flanks, and northwesterly extensions, of Mineral Ridge and beneath Rhyolite ridge (Plate
3). Conglomerates of Paleozoic clasts (“Ts1”) occupy the pre-Tertiary unconformity
below 2,000 stratigraphic feet of tuffaceous sediments and welded ashflows (“Ts2”),
rhyolitic airfall tuff (“Tafu”) and scattered flow-domes (“Tr”), and a latitic upper welded
ashflow (“Tawu”). The youngest Tertiary map unit is a 1,300-foot section of tuffaceous
sandstone, grit, and thin muds and freshwater limestone (“Ts3”) west of Rhyolite Ridge
(Plate 3). The Ts1 conglomerates, which may be as old as late Miocene, are over 5,600
feet thick just south of Mineral Ridge, thinning dramatically north and west to a few tens
of feet. A thick, early Miocene, ashflow section beneath the conglomerate is missing
along the crest of Mineral Ridge.
Intrusions, Mineral Ridge
The Mineral Ridge pluton (“T Jg”) forms the core of Mineral Ridge and consists
of peraluminous two-mica granite, granodiorite, and alaskite. Granite pegmatites cut all
bedding, foliation, and other granitic intrusions. Much of what Albers & Stewart (1972)
map as Wyman Formation (“wy”) on the northwest extensions of Mineral Ridge (Plate 3)
is actually porphyritic granite and granite gneiss with numerous, large, siltstone and
limestone zenoliths. Granite grades into quartzofeldspathic gneiss or even mylonite
approaching the Wyman contact, although the granite-Wyman contact itself is usually
sharp (2005 mapping and Brown, 2003, page 87). Foliation in the gneiss near the contact
often retains the original foliation attitudes of the wall rock.
All three phases of the Mineral Ridge pluton are intruded by coarse to very
coarse, irregular, quartz-feldspar-muscovite pegmatites; increasing in volume towards the
plutonic margins. Pluton margins may locally consist of over 50% pegmatite.
Lepidiolite, a lithium feldspar, has been reported in some the pegmatites (Albers &
Stewart, 1972, page 63).
Dark green mafic sills are often physically associated with Mineral Ridge quartz
lode gold deposits. They are commonly sheared and often propylitically altered to
chlorite, calcite, clays, and epidote (Brown, 2003, page 87).
Structure, Mineral Ridge
Precambrian and Paleozoic sediments describe a broad, faulted anticline parallel
to the northwest axis of Mineral Ridge. Thrust fault contacts, along with metamorphic
foliations in both sediments and plutonic gneiss, describe and enhance the Mineral Ridge
antiform as it drapes over the Mineral Ridge granitic pluton. Latest Cretaceous and
Tertiary extensional tectonics of the region have superimposed a complex pattern of
detachment, listric, and normal faults; including the northwesterly bounding fault on the
north side of Mineral Ridge and numerous steep northerly faults along the length of
Mineral Ridge and its western extensions (Plate 3).
Cataclasites, mylonites, and boudinage structures characterize the uppermost
foliated zone of the Mineral Ridge Pluton and adjacent phyllites and marbles. At least
two periods of fold deformation have occurred: 1) an early isoclinal folding associated
with development of metamorphic foliation, and 2) later open folding with vertical axial
planes. Isoclinal axial planes are generally strike N30ºE and dip 30ºSE. Open fold axes
generally strike N15ºW on the northeast flank of Mineral Ridge. Wavelengths are often
800 feet. Granite sills are common within the phyllites and calc-silicates of the Mineral
Ridge structural zone (Brown, 2003, pages 85 and 89).
Alteration, Mineral Ridge
Metamorphic alteration of the Wyman, Reed, and Deep Springs formations
consists of mica schist, calcite marble, and “calc-silicate” (calcite-epidote-quartzhornblende-muscovite) rocks. Regional metamorphism of the Wyman Formation
approaches almandine-amphibolite grade. The core granite and alaskite near wallrock
contacts exhibit foliation, lineation, and concordant zenoliths of gneiss, schist, and
marble.
The Wyman Formation near the pluton contact is separated into three alteration
units: proximal cataclasites, medial phyllitic calc-silicates, and distal phyllite-carbonates.
Proximal cataclasites are composed of up to 80% sheared, blue-gray calcite marble with
granite boudins and sheared diabase sills. Proximal cataclasites are the main hosts for
Mineral Ridge gold mineralization. Medial phyllitic calc-silicates are black to greenish
brown, thin-bedded, pelitic schistose hornfels and mica schist that weather brown.
Phyllitic calc-silicate textures range from granoblastic to banded granoblastic quartzfeldspar to banded schistose quartz-muscovite-feldspar-chlorite-quartz or hornblendealbite-quartz. Distal phyllite-carbonates consist of phyllites, phyllitic calcite and
dolomite marble, and siliceous dolomite.
Hydrothermal alteration includes retrograde propylitic alteration of Wyman
phyllites to a chlorite-albite-chloritoid assemblage. The Reed Dolomite is silicified
where associated with quartz veins (Brown, 2003, page 86).
Mineralization, Mineral Ridge
Gold, either native or as electrum, occurs in milky quartz fillings of shears within
proximal cataclasites formed in the Wyman Formation. Minor amounts of pyrite,
sphalerite, galena, chalcopyrite, and arsenopyrite are also often found in the milky quartz.
Gold particles encapsulated in the quartz ores are generally less than 50 microns and must
be finely crushed.
Three ore types have been identified: 1) “Main-Stage”, 2) breccias & stockworks,
and 3) banded veins. Main stage ores are milky to sugary vein quartz and breccia lenses,
often stacked and generally concordant with foliation. Main stage ore lenses are thickest
on steeper limbs of anticlinal folds. Main stage ores are thickest and highest grade in the
Mary Limestone member of the Wyman Formation. Replacement main stage ores also
occur in irregular bodies of Reed Dolomite.
Quartz veins, breccias, and vein stockworks occur in conjunction with main stage
quartz lodes and some felsic sills on the eastern slopes of Mineral Ridge. Vein
stockworks have also been mined in small, isolated occurrences by Golden Phoenix on
the crest of Mineral Ridge and high on its western slope.
Prospect Geology
Lithologies
Dominant rock type at the Roadrunner (Plate 6a) and Coyote Summit (Plate 7a)
prospects is the Mineral Ridge Pluton, consisting of granite, granite gneiss, and granite
pegmatite. Numerous zenoliths of brown, recrystallized, discontinuous, silty Wyman
limestone (mapping unit “m Ls”) denote the nearness of the pluton-sedimentary contact
at both prospects. Only two, very small, outcrops of Wyman siltstone were mapped at
Coyote Summit, but a singular zone of Wyman siltstone, curvilinear and about 1,000 feet
long by 250 feet wide was mapped at the Roadrunner prospect. Also at Roadrunner are
isolated blocks of recrystallized, blue-grey limestone mapped as the Deep Springs
Limestone by Albers & Stewart (1972, Plate 1). The Reed Dolomite has apparently been
tectonically removed from between the Wyman and Deep Springs formations, in a
manner similar to its thinning in the area of the Mary and Drinkwater mine workings
(Brown, 2003, page 38, para 3).
The Mineral Ridge pluton (granite, granite gneiss, and pegmatites) and Paleozoic
sedimentary wall rocks are overlain unconformably by Tertiary tuffaceous wacke and
siltstone (Ts2) at Roadrunner (Plate 6a). A sandy conglomerate no more than 10 feet
thick sometimes occurs at the base of the Tertiary volcaniclastics. The volcaniclastic
rocks at Roadrunner exceed thicknesses of 200 feet in some places, and are overlain by a
welded, crystal-rich, rhyolite ashflow (Tr).
Structure
At Coyote Summit (Plate 6a), structure is expressed primarily by foliation of
Wyman silty limestone zenoliths (m Ls) caught up in granite gneiss (“T Jg”). Pegmatites
in contact with Wyman zenoliths occur at the very southern edge of outcrop, at the
historic Coyote Summit workings, which may have included a primitive arrastra in earlier
days. Foliation appears to dip gently to moderately south overall. Pegmatites at the very
southern limit of outcrop contribute to the suggestion that the Pluton-Paleozoic contact
may be buried at shallow depths beneath alluvium to the south (SE section B-B’ and SW
section C-C’, Plate 5)
At Roadrunner (Plate 6a), structure is expressed by the Pluton-Paleozoic contact
and secondarily by foliation. As expressed by the intrusive contact, a monocline dips
increasingly to the west, disappearing beneath the basal Tertiary volcaniclastics (W
section A-A’ and NW section B-B’). Secondary open folds (see “District Structure”
above) are expressed in mapped foliation and lithologic geometry at Roadrunner. The
axial planes of these broad folds strike approximately East-West.
Alteration
Wyman siltstones are greenish, and appear propylitic, in rare outcrops at Coyote
Summit and Roadrunner, although silicified adjacent to the old Roadrunner workings.
Wyman limestones at both prospects are marbled, foliated and micaceous, whereas the
Deep Springs limestone is merely recrystallized with poorly developed foliation.
Mineralization
Milky quartz veinlets are parallel to, and crosscut, foliation at the Roadrunner
workings. Larger quartz lenses, though now mined, were subparallel to foliation as
developed in enclosing alaskite, gneiss and phyllite.
Thin, banded quartz veinlets occur as wide stockworks in one outcrop of greenish,
propylitic Wyman phyllite at location 15 at Roadrunner (yellow circle, Plate 6a), at the
western limit of Paleozoic outcrop. Goethite-limonite, after primary sulfides, forms the
innermost band of these 1 mm to 3 mm wide veinlets. Quartz banding is crystalline and
finely sugared. The most prominent veinlets are vertical and strike N40ºE. Gold/silver
ratio is about 5/1 in the surface-oxidized samples of Table 1.
Geochemistry
Table 1 – Tonogold 2004-2005 grab samples
Sample
No.
050401-16
040405-01
040405-04
102062
102063
102064
102065
102066
102067
102068
102069
102070
102071
102072
102073
102074
102075
102076
102077
102078
102079
102080
102081
102082
102083
Au
Au
Ag
UTM
UTM
Sample
ppm
opt
ppm
North
East
Description
431,005 Qv ±3" in dozer cut, goeth, trs pyr/ser.N35Wx20E
0.009
nil
0.000
0.0
0.000
0.0
4,185,529
0.008
0.000
0.0
4,185,530
430,908 Select dump grab incls vein & abun goet, trs pyr.
15.050
0.439
2.6
4,185,444
430,887 Dump grab from small prosp. w/qtz-rich alaskite
27.600
0.806
6.2
4,185,448
430,862 Select goet/lim stained alask w/min qv on dump
1.175
0.034
0.8
4,185,473
430,819 Rock chip in prosp, 8' radius, qtz/alask w/str feox
8.090
0.236
3.5
4,185,473
430,819 Select grab, higher grade material on prosp. Dump
nil
0.000
0.0
4,185,429
430,838 Random grab fr dump on ±30' shaft, alask w/feox
nil
0.000
0.0
4,185,414
430,886 Random grab fr dump on ±50' shaft, alask/shal barr?
0.000
1.2
4,185,341
431,014 Sel chip/grab of dozer cut dump, fe-stnd alask/sh/sch
nil
0.000
0.2
4,185,283
430,951 Sel dump grab, incl qv, sil metas. & loc. Str. Feox
nil
0.000
0.0
4,184,987
430,672 Sel chip/grab in small prosp & adj dump qv frags/feox
nil
0.000
0.0
4,185,146
430,969 Rock chip, 2' x 5' in vn/shr zone prosp qv w/vwk feox
0.039
0.001
0.4
4,184,146
431,167 Qv chip 1' x 2' vn E-W, 22ºS, wk feox
1.710
0.050
1.1
4,184,132
432,123 Sel grab of qv & feox stnd dump, 20' radius
0.313
0.009
0.2
4,183,609
432,212 Rock chip, 7' along 2' to 3' thk NE qv w/md-str feox
0.171
0.005
0.0
4,183,676
432,206 Sel dump grab of vn/vn bx, alt'd w/mod feox/pyr
0.024
0.001
0.0
4,183,672
432,323 Chip/chann samp in metsed w/mod feox 10' @ N23E
0.057
0.002
0.4
4,183,619
432,247 Chip in floor of doz cut/N20E alt'd zon w/sil-mod feox
0.013
0.000
0.0
4,184,007
432,202 Chip in metas/alask ledge w/min qtz/feox, N60W,25S
0.014
0.000
0.3
4,183,807
432,209 Chip in alt'd metas w/min silica/feox, N40E,62SE
0.049
0.001
0.3
4,183,862
432,314 Random grap fr dump in alt'd metas, N60W,12SW
0.022
0.001
0.0
4,183,622
432,165 Chip/chann samp, 8'N-S in alt'd metsed w/mod feox
0.008
Surface grab samples taken by Tonogold in September, 2004 (#102062 through
#102084), were assayed for gold and silver only. The highest Au values came from the
Roadrunner workings in quartz-veined alaskite and silicified phyllites (Plates 4a and 6a).
Geophysics
Prospect-scale geophysics specific to Roadrunner or Coyote Summit prospects are
not available.
Discussion
Gold values on the North Springs property exceed 0.80 opt Au in grab samples
from the Roadrunner workings. The most auriferous samples are examples of silicified
shears and veins in and near the granite-gneiss-schist contact, and are therefore smallscale duplicates of the “Main Stage” mineralization on the other side of Mineral Ridge
(see “Mineral Ridge mineralization”, above).
Host rock for gold at the Roadrunner prospect (Plate 6a) is quartz-veined and
silicified phyllitic siltstone (“Sts”) and alaskite and granite pegmatite apophyses (“T Jg”).
The enclosing limestones and phyllites of the Wyman Formation at Roadrunner are
gently folded around near-vertical, west-striking axial planes. Alteration of the Wyman
phyllite ranges from proximal silicic at the Roadrunner workings to distal propylitic
1,000 feet west, in a stream bed at the edge of the pre-Tertiary outcrop. The propylitic
phyllite at this location is cut by banded sugary quartz veinlets, the most prominent
striking N40ºE and dipping 90º (sample 050405-4, Table 1).
Gold mineralization at Roadrunner occurs along a gently dipping, undulating, but
planar sheared contact between high-level differentiates (alaskite, pegmatite) of the
Mineral Ridge pluton and the phyllites and limestone of the Wyman Formation.
Undulations in the contact zone seem to follow broad folds developed in the Wyman.
They also appear responsible for the outcrop pattern of the mineralized phyllite (“Sts”,
Plate 6a). Steep limbs of similar folds were always underground development targets for
mine operators on the northeast side of Mineral Ridge (Brown, 2003, page 85, para. 4).
The same methods for developing high-grade ore shoots should be applicable to the
Roadrunner mineralization: extensions of the mineralized “Sts” horizon (Plate 6a) could
be followed with a patterned drilling program to explore the pluton-sedimentary contact
as it steepens under post-mineral cover.
The Coyote Summit prospect occurs in granite, granite gneiss, alaskite, and
pegmatite with numerous zenoliths of Wyman limestone and phyllites. Intrusive textures
and abundance of Wyman zenoliths suggests the Coyote Summit mineralization was
proximal to the now-eroded intrusive-sedimentary contact. Local foliation patterns and
district-scale lithologic geometry suggest the intrusive-sedimentary contact is steepening
and may be preserved beneath alluvium southwest of the Coyote Summit workings
(Plates 3, 4b, 5, and 7a).
Conclusions
Areas of relatively steep intrusive-sedimentary contacts, better yet the steeper
limbs of folds, on the northeast side of Mineral Ridge are favored locations for larger
tonnages and better grades of “Main Stage” gold-bearing quartz lenses. On the southwest
side of Mineral Ridge, beneath the North Spring claims, the gold-mineralized intrusivesedimentary contact may steepen beneath thin Tertiary cover west and southwest of the
Roadrunner workings (Plate 6a) and beneath Quaternary alluvium southwest of the
Coyote Summit workings (Plate 7a). Both of these covered areas are adjacent to goldmineralized outcrops and should be explored by drilling. Geologic potential of the North
Spring target areas is comparable to the northeast side of Mineral Ridge, which produced
602,000 ounces of gold through 2002 (Brown, 2003, page 82).
Recommendations
The area of proposed North Springs gold potential (proposed 54-claim area)
should first be surveyed by ground magnetics, resistivity and perhaps CSAMT. The
resultant patterns should be interpreted in light of the undulating intrusive-sedimentary
contact projected beneath cover. Drill hole patterns should be designed to intercept
steeper portions of the proposed contact or any silicic shear zones interpreted from
geophysics.
A minimum of five “RC” holes each for Roadrunner and Coyote Summit is
recommended for the first drilling phase. Drilling should be designed, and continuously
redesigned during this first phase, to intercept the projected “Main Stage” horizon along
the steeper portions of the intrusive-sedimentary contact. Depths of this proposed first
round of drilling will probably not exceed 400 feet.
References
Albers, J.P. and J.H. Stewart, 1972, Geology and mineral deposits of Esmeralda County,
Nevada: Nevada Bureau of Mines and Geology Bulletin 78, 79 pages, 2 plates, 10
figures, 7 tables.
Brown, H.G. (editor), October 2003, Regional geology and gold deposits of the Silver
Peak area – mineralization hosted by metamorphic core complexes: Geological
Society of Nevada Fall Fieldtrip Guidebook, Special Publication No. 38, 211 pages.
Davis, S.R., October 2004, Preliminary geological review, North Springs project,
Esmeralda County, Nevada: private report for Tonogold Resources, Inc.