Release (Miranda Gold Corp), Nov 5, 2004
The Troy Property is located in the Grant Range of
northeastern Nye County, Nevada in the Humboldt National
Forest. It is approximately 150 km east of Tonopah,
Nevada and 230 km north of Las Vegas. The property
consists of 11 mineral claims covering approximately
91 ha (220 acres) on the western side of the Grant
Range, east of Railroad Valley.
Location Map Detailed
Geology and Mineralization
Troy’s historic underground workings are reported
to exploit oxidized shear zones internal to a large
bull-quartz vein. Historic production and exploration
resulted in over 800 m of underground drift in the
Locke Mine from 5 different adits in a 300 x 200 m
area. The property has not been drilled and
no modern exploration has been conducted.
Troy Surface Au Adits
An interesting highlight of the property is represented
in rock chip gold assays as high as 794ppm (25 opt)
gold, with nine rock chip samples from Troy’s underground
workings assaying above 40ppm (1.16 opt) gold.
Underground Au Values
Underground Au Values
The workings of the Locke mine are driven predominantly
within the large quartz body that is at or near the
contact of carbonate rocks in the hanging wall and
a granite intrusion in the footwall. The limestones
vary from massive, medium gray and re-crystallized
to very dark, strongly carbonaceous and sheared rocks.
Apparently the carbonate section is Cambrian age.
Intrusive rocks are presumed to be Tertiary but may
Troy Regional Geology
West of the Locke mine the large quartz body thins
and in places is not present but its position at the
contact of the carbonate section and the intrusion
is occupied by a consistent mylonite zone even where
quartz is absent. The mylonite zone strikes NE-SW
and dips approximately 20 degrees SE. There appears
to be a fault with similar attitude at the base of
the high limestone cliffs south of the Locke mine.
Significantly, the thickest portion of the massive
quartz body occupies a domed inflection in the limestone-granite
contact. The contact is dominantly if not exclusively
structural. Faults at the contact are well-exposed
underground. It appears that the thick, obvious quartz
body is related to regional-scale faulting and mylonitic
shearing and it is important to note that this massive
quartz is typically barren and does not represent
the primary target at Troy.
Troy Outcrop Geology
Ore Shoots in the Locke Mine
Within the large quartz body various workers have
obtained gold assays of up to approximately 3 opt
over several feet and multi-ounce gold in more selective
samples. Gold and silver mineralization occurs with
pyrite and arsenopyrite, and lesser sphalerite and
galena. Zones of strong limonite or manganese
staining tend to display stronger precious metal values.
Grayish, vaguely banded, cellular quartz distinct
from and cross-cutting the bull quartz observed locally
suggests that a secondary quartz event took place
after emplacement of the main bull-quartz vein.
Higher grade values are isolated and on historic sample
maps appear to be almost randomly scattered through
the massive quartz, however, careful examination reveals
that the higher grade portions of the mine are along
north-south striking, shallow easterly dipping faults
within the larger, massive quartz body. These discrete
ore shoots have strong iron-oxides (after sulfides)
and have a cellular/vuggy, grayish to dark red appearance.
It is obvious from stope development that this is
the material that was sought during historic mining.
Bat Adit 1.2oz
Three such structures appear to be present within
the existing workings: These fault-veins have named
by previous workers the A vein and B vein from east
to west respectively. A third poorly defined,
structure appears to be present at the western end
of the mine area above an ore chute system. The B
vein in the Locke Mine is apparently the same mineralized
structure that is exposed in workings on a prominent
ridge approximately 500ft west of the main Locke mine
portal. While the ore bodies are not proper veins,
and often can be characterized visually as fault zones,
for convenience sake they can be referred to (from
east to west) as A, B and C veins consistent with
earlier report nomenclature. Further sampling should
illustrate the nature of the “veins” and whether they
represent a consistent recognizable secondary quartz
event superposed on earlier bull-quartz.
Troy Underground ABC Veins
The north-south, east dipping ore-bearing structures
are cut off by a shallower fault at the hanging wall
of the massive quartz body. In the main Locke mine
the hanging wall fault above the quartz body has a
variable strike and appears to increase in plunge
downward to the south giving it a folded and domed
appearance. This fault may truncate the “A” vein down-dip
and to the east with probably a minor offset. Whether
the ore target extends into the hanging wall limestone
and the foot wall intrusion is unconfirmed: Regardless,
structures at the top and bottom of the quartz mass
will have cut it off and displaced it somewhat. Stope
widths are commonly 6 feet (2 meters) or slightly
Accounts of historic production report mill head
grades of averaging 0.345 to 0.571 ounces per ton
gold during the period from 1948 to 1950. Total
production is probably less than 1000 ounces of gold.
This is presumed to be primarily from stopes developed
on the “A” vein.
The target at Troy is for a mesothermal “fault-vein”
gold system overprinting the erratically mineralized
bull-quartz vein that has been the focus of historic
underground drifting. Multiple, discreet, sub parallel
stacked vein targets are suggested by the “A”, “B”
and “C” veins mapped in underground workings.
The style of gold-mineralization at Troy can be cautiously
called Pogo (Alaska)-like in that:
- gold and bismuth are associated suggesting a magmatic
- the main gold event appears temporally and possibly
tectonically distinct from an earlier metamorphic
(mylonitic) fabric enclosing the earlier main bull-quartz
- gold bearing fault-veins (fault zones with secondary
quartz (?)) are shallow dipping.
The Locke mine has not been tested by drilling. As
an intrusive associated mesothermal gold system, if
preliminary drilling shows that the north-south striking,
east dipping series of productive fault-veins extend
to depth below the south dipping bull-quartz body,
there is good potential for the discovery of significant
gold mineralization down-dip and laterally from the
District scale mapping also has a reasonable prospect
of resulting in discovery of new occurrences. Although
past production has been small, there has not been
any modern attempt to discover resources in the Locke
It is difficult to estimate the size potential of
the targets from existing underground workings but
it is certainly reasonable to expect the mineralized
structures to continue down-plunge for at least a
few hundred feet, and to have substantial lateral
extent. Structures at the top (as observed at
the upper surface in stopes) and probably at the bottom
of the bull-quartz mass will offset productive
fault-vein projections into the limestone hanging
wall and the granite footwall contact.
The thickness and attitude of the three recognized
ore-grade bearing fault-veins (A, B, C) targets
make them potentially amenable to underground mining
if suitable high-grade distributions in the shoots
(comparable to other mesothermal gold veins)
result in the upper end of or better than recorded
mill-head grades (0.571 opt gold) and ore shoot continuity
and depth and lateral extent can be demonstrated by
a preliminarily by a modest and relatively shallow
angle drill program.
Miranda is seeking a joint venture partner for the
Troy Project to conduct exploration in return for
An exploration program for Troy should include detailed
underground geologic mapping should be done with emphasis
on structural relationships. In conjunction with the
mapping program a detailed sampling program should
be done, particularly in the historic stopes.
Diamond drilling of targets to adequate test high-grade
on tight spacing from surface is suggested. While
much of the rock is competent, the mineralized quartz
will probably present modest drilling problems.
Miranda has completed limited underground mapping
and sampling to resolve productive veins and to confirm
and project inferred controls to high-grade. A simple
3D model derived from surface and underground mapping
and sampling has been constructed in order to target
high grade zones as well as fault and vein extensions.
Several proposed drill-holes have been planned and
can be visualized in the 3D model.
Troy Proposed Drill Holes
Summary of geochemical statistics for underground
rock chip samples with gold >0.1 opt. Summary statistics
for the 23 ore grade samples is shown in Table.