VANCOUVER,
April 11 /PRNewswire/ - Great Basin
Gold Ltd. ("Great Basin Gold" or the "Company"), (TSX: GBG; NYSE
Amex: GBG; JSE: GBG) updates exploration, stope and block
delineation results for its Hollister Project and Burnstone Mine.
At Hollister, highlights include results from the Velvet target
drilling, the emergence of another high grade pay shoot on the
Clementine #18 vein structure in the western part of the Hollister
orebody, and significant advances in the integration of existing
geological and geophysical data with new structural
interpretations, leading to a number of new exploration follow-up
targets.
HOLLISTER
Underground Exploration
Underground exploration and stope delineation
drilling has continued during the first quarter of 2011 (Q1 2011).
In total, two exploration holes at the Velvet target, fifteen
Blanket exploration holes (totaling 15,487 feet or 4,693 meters)
and twenty-four stope delineation holes (totaling 10,080 feet or
3,054 meters) were completed.
|
|
Velvet Target |
|
|
Two initial exploration holes have been completed, testing the
Velvet target north of the current mine infrastructure. The
boreholes were drilled at low angles across the Ordovician basement
strata, and were approximately 500 feet (160 meters) below the
Tertiary volcanic unconformity. HDB-432 was drilled laterally
to 3,383 feet (1,025 meters) and HDB-433 to 2,854 feet (865
meters). Of note, the current Hollister mine development, exposing
the Gwenivere and Clementine vein systems, extends vertically from
5,050 to 5,425 feet (1,530 to 1,644 meters) above mean sea level.
HDB-432 tested to an elevation of 4,600 feet (1,394 meters) and
HDB-432 to 5,000 feet (1,515 meters) above mean sea level.
Highlights of the drilling are shown below. |
Velvet Target Intersections
Veins |
Drill Hole
ID |
Vein
Intersection (ft) |
Drilled
Thickness
(ft) |
True
Width
(ft) |
Analytical
Results |
Vein System |
Vein
ID |
From |
To |
Au
(opt) |
Au
(g/t) |
Ag (opt) |
Ag (g/t) |
Gloria?
Gloria? |
VN25
VN26 |
HDB-432
HDB-432 |
648.2
703.1 |
649.2
703.8 |
1.0
0.7 |
|
0.065
0.104 |
2.24
3.55 |
7.5
5.5 |
255
190 |
Velvet
Velvet
Velvet
Velvet |
|
HDB-432
HDB-432
HDB-432
HDB-432 |
875.4
901.9
1047.1
1109.8
|
879.8
906.5
1052.3
1116.7
|
4.4
4.6
5.2
6.9 |
|
Silicification & brecciation, low grade Au
Silicification & brecciation, low grade Au
Silicification & brecciation, low grade Au
Silicification & brecciation, low grade Au |
Gloria? |
VN25 |
HDB-433 |
635.0 |
635.6 |
0.6 |
|
0.106 |
3.64 |
5.0 |
173 |
Velvet
Velvet
Velvet
Velvet
Velvet
Velvet
Velvet
|
-
-
-
-
|
HDB-433
HDB-433
HDB-433
HDB-433
HDB-433
HDB-433
HDB-433
|
1314.1
1370.8
1438.5
1594.2
2310.8
2607.5
2766.6 |
1326.9
1373.6
1447.0
1604.7
2333.4
2607.8
2795.0 |
12.8
2.8
8.5
10.5
22.6
5.3
28.4
|
8.5
10.5
22.6
5.3
28.4 |
Silicification & brecciation, low grade Au &Ag
Silicification/veining elevated Au
Silicification/veining
Silicification
Silicification/veining elevated Au
Quartz veining & silicification
Silicification |
A number of significant silver assays (5.5 to
7.4 opt Ag, 190 to 255 g/t Ag) with anomalous gold values were
received in the 630 to 705-foot (210 to 240-meter) zones. These are
interpreted to be southerly extensions of the Gloria vein system
some 6,000 feet (1,820 meters) to the north-northwest. The
correlation would imply structural continuity with the Gloria vein
system and, as such, constitutes a very significant vein extension
target, requiring further exploration drilling. The metal zoning is
considered indicative of mineralized structures in the lower zones
of a Hollister equivalent epithermal mineral system.
Borehole HDB-432 also intersected multiple
mineralized vein and silicified zones between 875 and 1,117 feet
(265 to 338 meters). HDB-433 intersected similar zones between
1,314 and 2,795 feet (398 to 847 meters). The silicified zones
ranged from 2.6 to 28.4 feet (0.8 to 8.6 meters) in width. These
zones correlate with existing structural features as well as
historic mercury diggings such as Butte #2 and Velvet north of the
current mine development. Multi-element geochemical analyses and
clay mineralogy studies are in progress. The Velvet targets will be
further tested by surface drilling during the upcoming summer field
season.
Blanket Zone
During the quarter fifteen boreholes were
completed, testing the extensions of Blanket zone mineralization
exposed by trial mining at 3000N 1E; assays from nine boreholes are
still awaited. The drilling is indicating structural cutoffs of
this mineralization in-line with the structures controlling the
Clementine #18 vein pay shoot below.
The evaluation strategy for the Blanket zone
mineralization is being modified as mining and drilling advance. It
is clear that the bulk sample exposures are proving to be a more
accurate in evaluating the variable extent of the bonanza grade
mineralization. Planned infrastructure will allow ramping up to
5478 level, followed by phased short distance fan drilling.
The close relationship of the development of
bonanza grades with underlying high grade "pay-shoot" epithermal
veins is becoming evident. As a consequence, the Blanket drilling
program is being modified and extended to test other targets within
the mine development.
Stope Delineation
The stope delineation drilling has continued
evaluating the main Gwenivere (#8) and Clementine (#14-19) veins.
Of note is
- the emergence of another significant pay shoot on and around
the Clementine #18 structure, in the western section of the mine,
from which trial mining is currently grading at a diluted average
of 2.844 opt (97.50 g/t) Au and 22.2 opt (761 g/t) Ag over stope
lengths of approximately 162 feet (49 meters) and average vein
width of 2.4 feet (0.73 meters);
5050 WB 8 sub 2 &
9 sub 1 Trial Stopes |
|
Stope
Length
Feet |
Average
vein width
feet |
Average
vein Au
oz/ton |
Average
vein Ag
oz/ton |
Average
Dilution
Au oz/ton |
Average
Dilution
Ag oz/ton |
WB9 Sub1 |
169 |
2.5 |
7.819 |
52.1 |
2.818 |
19.8 |
WB8 Sub2 |
156 |
2.3 |
6.170 |
58.0 |
2.881 |
25.4 |
Average |
|
2.4 |
7.145 |
54.5 |
2.844 |
22.1 |
and
- the intersection of a number of unmodelled veins (VN #99) with
significant gold and silver grades. These are interpreted as splays
of existing high grade veins.
Highlight Stope Delineation
Intersections
Veins |
Drill Hole
ID |
Vein
Intersection (ft) |
Drilled
Thickness
(ft) |
Analytical
Results |
Vein System |
Vein ID |
From |
To |
Au
(opt) |
Au
(g/t) |
Ag
(opt) |
Ag
(g/t) |
Clementine
Clementine
Clementine |
VN15
VN18
VN18 |
HDB11-442
HDB11-445
HDB11-445 |
137.3
296.8
|
139.3
299
including |
2.0
2.2
0.8 |
1.177
0.945
1.516 |
40.34
32.40
51.98 |
0.6
2.2
3.9 |
20
76
132 |
Clementine |
VN17 |
HDB11-446 |
293 |
293.6 |
0.6 |
2.704 |
92.72 |
13.0 |
446 |
Gwenivere |
VN8 |
HDB11-470 |
36.8 |
37.4 |
0.6 |
3.491 |
119.70 |
17.2 |
591 |
Clementine
Clementine
Clementine
Clementine |
VN17
VN18
VN18
VN19 |
HDB11-470
HDB11-470
HDB11-470
HDB11-470 |
247.2
283.9
288.9
306.9 |
248
285.4
289.4
307.5 |
0.8
1.5
0.5
0.6 |
1.837
11.579
1.772
1.652 |
62.98
397.00
60.76
56.64 |
12.5
39.3
7.4
16.5 |
429
1346
254
567 |
Clementine |
VN13 |
HDB11-472 |
199.3 |
200 |
0.7 |
4.941 |
169.40 |
15.0 |
515 |
Clementine |
VN15 |
HDB11-475 |
83 |
84 |
1.0 |
4.769 |
163.50 |
49.5 |
1697 |
Clementine
Clementine |
VN8
VN99 |
HDB11-476
HDB11-476 |
26
61 |
26.7
61.4 |
0.7
0.4 |
4.509
1.076 |
154.60
36.90 |
12.2
16.1 |
420
551 |
Clementine
Clementine |
VN99
VN99 |
HDB11-478
HDB11-478 |
104.4
243 |
105.1
243.5 |
0.7
0.6 |
3.179
0.800 |
109.00
27.43 |
13.5
16.4 |
463
563 |
Clementine |
VN16 |
HDB11-479 |
231.7 |
236.3 |
4.8 |
0.963 |
33.00 |
31.9 |
1094 |
Surface Exploration
Nevada Bureau of Land Management (BLM) approvals
for surface drilling at Hollister have been received. Budgeting and
planning of the surface exploration drilling for Q2-Q3 2011 are now
being advanced, and include a further eight boreholes on the Hatter
Graben target and surface follow up of the Velvet underground
drilling.
Significant progress has also been made on the
sub-regional and minesite scale collation and interpretation of
geophysical data, specifically, airborne magnetic, ground CSMAT
(high resolution resistivity), and gravity. This work is in process
of being integrated with a first-pass structural interpretation of
the larger Hollister area. The structural work has significantly
advanced the understanding of the timing and geometry of ore fluid
controlling basement structures, given that the Hollister
mineralization is approximately 15 million years old, and hosted in
430 million year old Vanini metasedimentary rocks and unconformably
overlying 16 million year old mid Miocene volcanic rocks.
The whole target rationalization and
prioritization at Hollister is in the process of being reviewed,
and there are number of new plays to be investigated over the
forthcoming exploration drilling seasons. These include a number of
structures that are similar to those that control the geometry of
the Gwenivere and Clementine vein systems. To the southeast,
altered intrusive rocks have been interpreted from the geophysical
data, interfacing with the Hatter Graben vein system. A further
phase of surface drilling is planned for the Hatter Graben during
Q3 2011. The existence of Carlin age (38-43 Million year old)
mineralization in the southeastern portion of the claim block
cannot be ruled out. In this area, a conspicuous structural
interface with the Carlin Trend has been identified which warrants
further investigation. CSMAT high resolution resistivity data
is being integrated with empirical borehole data, and a number of
new vein system targets are emerging from this work.
BURNSTONE
Underground and Surface Exploration
Infill drilling from surface is being undertaken
to tighten up on the evaluation and structural geometry of certain
mining blocks. Results received during Q1 2011 are tabulated
below.
Summary Burnstone Mine Surface Drilling
Intersections Q1 2011
Drill Hole
ID |
Intersection |
Reef
Width
Cm |
Geology |
Au Grade
g/t |
Au Content
cmg/t |
Target Area
|
From |
To |
Cm |
BGM029 |
392.66 |
393.07 |
41 |
38 |
Kimberley Reef |
13.48 |
512 |
B2 SOUTH WEST |
BGM048 |
462.71 |
463.20 |
49 |
45 |
Kimberley Reef |
1.55 |
70 |
B2 SOUTH WEST |
BGM049 |
283.30 |
283.82 |
52 |
48 |
Kimberley Reef |
9.72 |
467 |
B2 NORTH |
BGM050 |
277.46 |
277.60 |
14 |
12 |
Kimberley Reef |
1.12 |
13 |
B2 NORTH |
BGM051 |
335.47 |
336.06 |
59 |
57 |
Kimberley Reef |
5.70 |
325 |
C-UP |
BGM052 |
416.83 |
417.07 |
24 |
21 |
Kimberley Reef |
16.64 |
349 |
B2 NORTH WEST |
Underground evaluation is principally effected
by channel sampling of exposed sidewalls of development drives and
stope panels. Horizontal or shallow dipping cover drilling is
undertaken for development control. Over 10,000 channel
samples have been taken to date. During Q1, 2,686 channel samples
were taken. The summary gold grade (g/t), channel width (cw) and
gold content (cmg/t) statistics for the various mining blocks are
shown below.
Block |
#
Samples |
Channel
Width
cm |
Gold
Content
cmg/t |
Gold
Grade
Au g/t |
B2 |
1,956 |
56 |
461 |
8.22 |
B3 |
6,441 |
101 |
276 |
2.74 |
C3 |
1,162 |
32 |
559 |
17.61 |
Decline 1287 |
531 |
73 |
442 |
6.09 |
1320 Access |
54 |
23 |
415 |
18.04 |
C-Upper |
190 |
65 |
902 |
13.93 |
Connecting 5 |
147 |
25 |
184 |
8.05 |
Decline Loop |
177 |
70 |
222 |
3.26 |
Decline |
94 |
42 |
210 |
4.87 |
Raise-4A |
34 |
9 |
26 |
2.74 |
Overall |
10,786 |
81 |
473 |
5.88 |
These results are in-line with or better than mine development
expectations. Although current channel widths are skewed due to the
higher number of samples for Block B3 sampling, the Life-of-Mine
plan indicates an average channel width of 68 cm.
Surface Exploration Outside the Burnstone Mining
Right
Surface exploration has recommenced at
Burnstone, with the initiation of the shallow basin edge target
evaluation program, run under the South Rand Basin Project.
Historic surface diggings and limited stoping of the Kimberley Reef
is being investigated on the farm Rietbult, approximately 7
kilometers northwest from the Burnstone Mine infrastructure. The
first two diamond holes intersected a Kimberley Reef stope
approximately 55 meters below surface, and the Kimberley Reef at 87
meters below surface. Assay results are awaited. Previous
exploration in the area included historic drilling in the 1960's,
as well as validation underground channel sampling of reef
exposures. This work, albeit restricted in extent, showed the
Kimberley Reef to be narrow (10 to 30 cm) but with grades ranging
from trace to 35 g/t Au. The current drilling program will
test in the order of 4 kilometers of potential strike, with a view
to evaluating satellite, shallow, narrow reef/high grade
underground development.
Ferdi Dippenaar,
Great Basin Gold President and CEO, commented: "Our decision to
continue with exploration at Hollister during 2010 continues to
deliver results. The emergence of a new payshoot will deliver
short-term benefits, and our work on the larger Hollister Property
indicates the existence of a similar orebody to the one currently
being trial mined. The geological teams at both Hollister and
Burnstone are continuing to hone their evaluation and exploration
skills. An excellent geological and structural platform is
emerging at Hollister for the discovery of further gold and
silver-bearing vein systems. Continued integration of the data
available is paying dividends in improving our predictive
models. At Burnstone, the team is integrating existing
geological information with the detail afforded by underground
exposures. This will, in due course, provide real-time updating of
the geological and structural models, which will, in turn, assist
with short to medium term mine planning."
Technical information herein has been reviewed
and approved by Phil Bentley,
Pr.Sci.Nat., Great Basin Gold's Vice President: Geology &
Exploration. Mr Bentley is a Qualified Person as defined by
Canadian Securities Regulations in National Instrument 43-101.
Ferdi
Dippenaar
President and CEO
Samples collected from the Hollister Project are delivered to
Inspectorate America Corporation (Inspectorate) in Sparks,
Nevada. Vein samples are analyzed by standard fire assay
procedures. For standard fire assay, vein sample preparation
consists of drying and jaw-crushing the entire sample to 90%
passing 10-mesh, taking a 300 g sub-sample using a Jones splitter,
and then pulverizing the 300 g sub-sample to 90% passing 150-mesh
using a large capacity ring and puck pulverizer. A 30 g
charge is fire assayed. All metal determinations are by
gravimetric finish. Laboratory Quality Assurance/Quality
Control (QA/QC) is monitored using coarse reject blanks and assay
standards, duplicate fire assays, and Inspectorate's internal
standards and blanks. Coarse blanks (barren rhyolite or
landscape marble) and assay standards are inserted into the sample
sequence as blind samples prior to submitting the samples to the
laboratory. Inspectorate also inserts assay standards and
blanks into the sample stream. QA/QC results are within
acceptable limits.
Samples collected from the Burnstone Mine are delivered to ALS
Chemex in Johannesburg, South Africa. Borehole core and
channel samples of Kimberley Reef are analyzed by standard fire
assay procedures. For standard fire assay, vein sample
preparation consists of drying and jaw-crushing the entire sample
to 70% passing 10-mesh (2mm), taking a 400 g sub-sample using a
Jones splitter, and then pulverizing the 400 g sub-sample to 90%
passing 150-mesh using a large capacity ring and puck
pulverizer. Three 50 g charges are fire assayed. All
metal determinations are by gravimetric finish. Laboratory
Quality Assurance/Quality Control (QA/QC) is monitored using coarse
reject blanks and assay standards, duplicate fire assays, and ALS
Chemex internal standards and blanks. Coarse blanks (barren
basalt or quartzite) and assay standards are inserted into the
sample sequence as blind samples prior to submitting the samples to
the laboratory. ALS Chemex also inserts assay standards and
blanks into the sample stream. QA/QC results are within
acceptable limits. |
This document contains "forward-looking
statements" that were based on Great Basin Gold's expectations,
estimates and projections as of the dates as of which those
statements were made. Generally, these forward-looking statements
can be identified by the use of forward-looking terminology such as
"outlook", "anticipate", "project", "target", "believe",
"estimate", "expect", "intend", "should" and similar expressions.
Forward-looking statements are subject to known and unknown risks,
uncertainties and other factors that may cause the Company's actual
results, level of activity, performance or achievements to be
materially different from those expressed or implied by such
forward-looking statements. These include but are not limited
to:
- uncertainties and costs related to the Company's exploration
and development activities, such as those associated with
determining the extent of mineral resources or reserves which
exist on a property;
- uncertainties related to feasibility studies that provide
estimates of expected or anticipated costs, expenditures and
economic returns from a mining project; uncertainties related to
expected production rates, timing of production and the cash and
total costs of production and milling;
- uncertainties related to the ability to obtain necessary
licenses, permits, electricity, surface rights and title for
development projects;
- operating and technical difficulties in connection with mining
development activities;
- uncertainties related to the accuracy of our mineral reserve
and mineral resource estimates and our estimates of future
production and future cash and total costs of production, and the
geotechnical or hydrogeological nature of ore deposits, and
diminishing quantities or grades of mineral reserves;
- uncertainties related to unexpected political, judicial
or regulatory proceedings;
- changes in, and the effects of, the laws, regulations and
government policies affecting our mining operations, particularly
laws, regulations and policies relating to
-
- mine expansions, environmental protection and associated
compliance costs arising from exploration, mine development, mine
operations and mine closures;
- expected effective future tax rates in jurisdictions in which
our operations are located;
- the protection of the health and safety of mine workers;
and
- mineral rights ownership in countries where our mineral
deposits are located, including the effect of the Mineral and
Petroleum Resources Development Act (South Africa);
- changes in general economic conditions, the financial markets
and in the demand and market price for gold, silver and other
minerals and commodities, such as diesel fuel, coal, petroleum
coke, steel, concrete, electricity and other forms of energy,
mining equipment, and fluctuations in exchange rates, particularly
with respect to the value of the U.S. dollar, Canadian dollar and
South African rand;
- unusual or unexpected formation, cave-ins, flooding, pressures,
and precious metals losses (and the risk of inadequate insurance or
inability to obtain insurance to cover these risks);
- changes in accounting policies and methods we use to report our
financial condition, including uncertainties associated with
critical accounting assumptions and estimates;
- environmental issues and liabilities associated with mining
including processing and stock piling ore;
- geopolitical uncertainty and political and economic instability
in countries which we operate; and
- labour strikes, work stoppages, or other interruptions to, or
difficulties in, the employment of labour in markets in which we
operate mines, or environmental hazards, industrial accidents or
other events or occurrences, including third party interference
that interrupt the production of minerals in our mines.
For further information on Great Basin Gold,
investors should review the Company's annual Form 40-F filing with
the United States Securities and Exchange Commission www.sec.com
and home jurisdiction filings that are available at
www.sedar.com.
SOURCE Great Basin Gold Ltd.