Great Basin Gold Updates Exploration and Drilling Results for Hollister Project and Burnstone Mine
11.04.2011 | CNW
VANCOUVER, April 11 /CNW/ - 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 | | Vein | | | Analytical Results |
| | Drill |Intersection | Drilled |True | |
| | Hole | (ft) |Thickness|Width| |
|____________| ID |_____________| (ft) |(ft) |__________________________|
| Vein |Vein| | From | To | | |Au (opt)|Au | Ag | Ag |
|System | ID | | | | | | |(g/t)|(opt)|(g/t)|
|_______|____|_______|______|______|_________|_____|________|_____|_____|_____|
|Gloria?|VN25|HDB-432|648.2 |649.2 | 1.0 | | 0.065 |2.24 | 7.5 | 255 |
|Gloria?|VN26|HDB-432|703.1 |703.8 | 0.7 | | 0.104 |3.55 | 5.5 | 190 |
|_______|____|_______|______|______|_________|_____|________|_____|_____|_____|
|Velvet | |HDB-432|875.4 |879.8 | 4.4 | | Silicification & |
|Velvet | |HDB-432|901.9 |906.5 | 4.6 | |brecciation, low grade Au |
|Velvet | |HDB-432|1047.1|1052.3| 5.2 | | Silicification & |
|Velvet | |HDB-432|1109.8|1116.7| 6.9 | |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 | |HDB-433|1314.1|1326.9| 12.8 | | Silicification & |
|Velvet | |HDB-433|1370.8|1373.6| 2.8 | |brecciation, low grade Au |
|Velvet | - |HDB-433|1438.5|1447.0| 8.5 | 8.5 | &Ag |
|Velvet | - |HDB-433|1594.2|1604.7| 10.5 |10.5 | Silicification/veining |
|Velvet | - |HDB-433|2310.8|2333.4| 22.6 |22.6 | elevated Au |
|Velvet | - |HDB-433|2607.5|2607.8| 5.3 | 5.3 | Silicification/veining |
|Velvet | |HDB-433|2766.6|2795.0| 28.4 |28.4 | 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| Average |Average|Average| Average | Average |
| | Feet |vein width|vein Au|vein Ag|Dilution |Dilution |
| | | feet |oz/ton |oz/ton |Au oz/ton|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 | | Vein | Drilled | Analytical Results |
| | Drill | Intersection |Thickness| |
| | Hole | (ft) | (ft) | |
|_______________| ID |________________| |___________________________________|
| Vein |Vein| | | | | Au | Au | Ag | Ag |
| System | ID | |From | To | |(opt) |(g/t) |(opt) |(g/t) |
|__________|____|_________|_____|__________|_________|________|________|________|________|
|Clementine|VN15|HDB11-442|137.3| 139.3 | 2.0 | 1.177 | 40.34 | 0.6 | 20 |
|Clementine|VN18|HDB11-445|296.8| 299 | 2.2 | 0.945 | 32.40 | 2.2 | 76 |
|Clementine|VN18|HDB11-445| |including | 0.8 | 1.516 | 51.98 | 3.9 | 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|VN17|HDB11-470|247.2| 248 | 0.8 | 1.837 | 62.98 | 12.5 | 429 |
|Clementine|VN18|HDB11-470|283.9| 285.4 | 1.5 | 11.579 | 397.00 | 39.3 | 1346 |
|Clementine|VN18|HDB11-470|288.9| 289.4 | 0.5 | 1.772 | 60.76 | 7.4 | 254 |
|Clementine|VN19|HDB11-470|306.9| 307.5 | 0.6 | 1.652 | 56.64 | 16.5 | 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|VN8 |HDB11-476| 26 | 26.7 | 0.7 | 4.509 | 154.60 | 12.2 | 420 |
|Clementine|VN99|HDB11-476| 61 | 61.4 | 0.4 | 1.076 | 36.90 | 16.1 | 551 |
|__________|____|_________|_____|__________|_________|________|________|________|________|
|Clementine|VN99|HDB11-478|104.4| 105.1 | 0.7 | 3.179 | 109.00 | 13.5 | 463 |
|Clementine|VN99|HDB11-478| 243 | 243.5 | 0.6 | 0.800 | 27.43 | 16.4 | 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
_____________________________________________________________________
| | Intersection | | |Au Grade|Au Content| |
|Drill |________________|Reef | | g/t | cmg/t | Target |
|Hole ID| From | To |Cm|Width|Geology | | | Area |
| | | | | Cm | | | | |
| | | | | | | | | |
|_______|______|______|__|_____|_________|________|__________|________|
|BGM029 |392.66|393.07|41| 38 |Kimberley| 13.48 | 512 |B2 SOUTH|
| | | | | | Reef| | | WEST |
|_______|______|______|__|_____|_________|________|__________|________|
|BGM048 |462.71|463.20|49| 45 |Kimberley| 1.55 | 70 |B2 SOUTH|
| | | | | | Reef| | | WEST |
|_______|______|______|__|_____|_________|________|__________|________|
|BGM049 |283.30|283.82|52| 48 |Kimberley| 9.72 | 467 |B2 NORTH|
| | | | | | Reef| | | |
|_______|______|______|__|_____|_________|________|__________|________|
|BGM050 |277.46|277.60|14| 12 |Kimberley| 1.12 | 13 |B2 NORTH|
| | | | | | Reef| | | |
|_______|______|______|__|_____|_________|________|__________|________|
|BGM051 |335.47|336.06|59| 57 |Kimberley| 5.70 | 325 | C-UP |
| | | | | | Reef| | | |
|_______|______|______|__|_____|_________|________|__________|________|
|BGM052 |416.83|417.07|24| 21 |Kimberley| 16.64 | 349 |B2 NORTH|
| | | | | | Reef| | | 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.
___________________________________________
| | No. |Channel| Gold | Gold |
| Block |Samples| Width |Content|Grade |
| | | cm | cmg/t |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
o mine expansions, environmental protection and associated compliance
costs arising from exploration, mine development, mine operations
and mine closures;
o expected effective future tax rates in jurisdictions in which our
operations are located;
o the protection of the health and safety of mine workers; and
o 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.
For further information:
For additional details on Great Basin Gold Ltd. and its gold properties, please visit the Company's website at www.grtbasin.com or contact Investor Services:
Tsholo Serunye in South Africa 27 (0)11 301 1800
Michael Curlook in North America 1 888 633 9332
Barbara Cano at Breakstone Group in the USA (646) 452-2334