Silverstone Releases Initial Mineral Resource Estimate for Its Copala Silver Project, Sinaloa State, Mexico
22 July 2008 - 11:00PM
Marketwired
VANCOUVER, BRITISH COLUMBIA -
Highlights
- Initial independent mineral resource estimate completed for
Copala silver project, Sinaloa State, Mexico
- Copala mineral resource estimate at the underground Animas
Refugio Vein at a 90 g/t silver cut-off grade totals:
-- Indicated category: 656,000 tonnes at a grade of 204 gpt
silver and 1.1 gpt gold, containing 4.3 million ounces of silver
and 23,000 ounces of gold or 5.5 million silver equivalent
ounces(1)
-- Inferred category: 345,000 tonnes at a grade of 145 gpt
silver and 0.8 gpt gold, containing 1.6 million ounces of silver
and 9,000 ounces of gold or 2.1 million silver equivalent
ounces(1)
- Copala resource estimate at the surface La Colorada
Vein-Mantos at 20 g/t silver equivalent(1) cut-off grade
totals:
-- Inferred resource: 2.5 million tonnes at a grade of 80 gpt
silver and 0.4 gpt gold, containing 6.5 million ounces of silver
and 30,700 ounces of gold or 8.1 million silver equivalent
ounces(1)
Initial current mineral resource estimates of two
well-mineralized zones on the Copala silver project have been
completed by independent qualified person, as defined by NI 43-101,
Robert Sim, P.Geo. Hugh Willson, P.Geo., is the company's qualified
person as defined by NI 43-101. Both have reviewed the contents of
this news release.
To date, Silverstone has focused its drilling on two of the more
than 9 known vein and manto systems on the Copala Property. These
are the Animas Refugio vein and La Colorada vein-mantos.
On the Animas Refugio vein system, Silverstone has drilled 131
holes that total 15,184 meters. This drilling was distributed
between four sectors that host historic workings: La Pipa, El
Muerto, Clemens, and San Carlos. Vein mineralization in the
combined Clemens-El Muerto Sector showed sufficient grade and
continuity to warrant infill drilling with a goal of identifying a
resource with potential to be developed by underground mining.
The Animas Refugio and La Colorada mineral resource estimates
have been generated from drill hole sample assay results and the
interpretation of geologic models, which relate to the spatial
distribution of silver and gold. Interpolation characteristics have
been defined based on the geology, drill hole spacing and
geostatistical analysis of the data.
Mineral resources on the Animas Refugio Vein have been generated
using the inverse distance weighting interpolation method with a
nominal 2x5x2 meter block size. The long axis of the blocks are
oriented parallel to the vein at an azimuth of 315 degrees.
On the La Colorada vein system, Silverstone has focused on an
area with significant historic workings in a vein-mantos system,
which occurs at varying depths from 0 to 50m below surface.
Silverstone has drilled 64 diamond drill holes totaling 6,454
meters in the La Colorada zone. Mineral resources at the La
Colorada zone are generated using the inverse distance weighting
interpolation method with a nominal 5 meter block size.
Both deposits were subjected to significant capping of high
grade due to drill hole spacing. This capping reduced the overall
silver equivalent for the two zones by over 2 million ounces. It is
believed that the historic mining at Copala was focused on high
grade mineralization. It is management's opinion that additional
drilling and sampling may increase the population of high grade
samples and result in less silver losses due to capping.
The following Summary Tables 1, 2 and 3 show overall project
resource estimates at two silver cut-offs of 30 g/t and 90 g/t for
the Aminas Refugio vein, reflecting underground operating
conditions, and 20 g/t and 50 g/t silver equivalent for the La
Colorada mantos, reflecting a potential open pit scenario.
Table 1: TOTAL INDICATED RESOURCES - ANIMAS REFUGIO VEIN
---------------------------------------------------------------------
Silver
Cut Off Tonnes Silver Gold Silver Gold Equivalent
(Ag gpt) (000's) (gpt) (gpt) (000's oz) (000's oz) (000's oz)
---------------------------------------------------------------------
30 1,273 132 0.74 5,405 30 6,905
---------------------------------------------------------------------
90 656 204 1.11 4,307 23 5,457
---------------------------------------------------------------------
Table 2: TOTAL INFERRED RESOURCES - ANIMAS REFUGIO VEIN
---------------------------------------------------------------------
Silver
Cut Off Tonnes Silver Gold Silver Gold Equivalent
(Ag gpt) (000's) (gpt) (gpt) (000's oz) (000's oz) (000's oz)
---------------------------------------------------------------------
30 1,176 81 0.48 3,054 18 3,954
---------------------------------------------------------------------
90 345 145 0.79 1,605 9 2,055
---------------------------------------------------------------------
Table 3: TOTAL INFERRED RESOURCES - LA COLORADA MANTOS
---------------------------------------------------------------------
Cut Off Silver
Ag Eqv Tonnes Silver Gold Silver Gold Equivalent
(gpt) (000's) (gpt) (gpt) (000's oz) (000's oz) (000's oz)
---------------------------------------------------------------------
20 2,527 80.2 0.38 6,516 30.7 8,051
---------------------------------------------------------------------
50 1,902 97.5 0.46 5,963 28 7,363
---------------------------------------------------------------------
Note: (1) Silver equivalent is calculated by multiplying Gold grade
by 50. No metallurgical recoveries were included.
(i) Resources are not mineral reserves as the economic
viability has not been demonstrated.
(ii) 1 kilogram equals 2.2 lbs; 31.103 grams equals 1 oz Troy.
Full resource tables related to the above totals for the initial
resource estimates are available on the Company's website
www.silverstonecorp.com.
The exploration programs at Copala by Capstone Gold and
subsequently Silverstone Resources Corp. were supervised by
qualified person Hugh Willson, Vice President of Exploration for
Silverstone. A quality control and assurance protocol was utilized
on the project including blanks, standards and duplicates with each
batch of assays. Silverstone's samples were assayed by ALS Chemex
in Vancouver. Core duplicate samples were sent to SGS Lakefield for
analysis in Toronto. The independent resource estimation was done
by qualified person Robert Sim of Sim Geological Inc. A detailed
43-101 compliant technical report on this resource estimate will be
co-authored by qualified persons Robert Sim of Sim Geological Inc.
and Hugh Willson, VP Exploration of Silverstone Resources Corp. The
report will be available on the Company's web site and
www.sedar.com within 45 days.
2008 Copala Exploration Program
Silverstone is planning additional exploration on other manto
zones at Copala in the 4th quarter of 2008 after the rainy season
abates.
In addition, Silverstone is currently undertaking a
property-wide stream sediment program that will aid the evaluation
of the other veins and mantos that have not been drill-tested to
date. Anomalous zones identified by this program will be followed
up by detailed mapping, sampling, and drilling if warranted.
ABOUT SILVERSTONE
Silverstone is a Canadian based public silver mining company
with 100% of its revenue from silver production. More information
is available online at: www.silverstonecorp.com.
Contacts: Silverstone Resources Corp. Chris Tomanik (604)
637-8151 Email: ctomanik@silverstonecorp.com Silverstone Resources
Corp. Mark Patchett (604) 637-8151 (604) 688-2180 (FAX) Email:
mpatchett@silverstonecorp.com Website: www.silverstonecorp.com
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