Great Basin Gold Revises Hollister Mineral Resources Based On Trial Mining & Drilling Results: Gold Equivalent Ounces Increase By 27%



    VANCOUVER, June 17 /CNW/ - Great Basin Gold Ltd. ("Great Basin Gold" or
the "Company"), (TSX: GBG; NYSE Amex:   GBG; JSE: GBG) announced today that a
revised mineral resource estimate had been completed for the Company's
Hollister Project on the Carlin Trend in Nevada, USA. The overall contained
gold equivalent ounces at Hollister have increased by 27% from 2.3 million in
June 2008 to 2.9 million(1). At a cut-off grade of 0.25 oz/ton (8.57 g/t Au),
the combined measured and indicated mineral resources contain 1.45 million
gold equivalent ounces grading 1.167 oz/ton (40.00 g/t) for gold and 8.59
oz/ton (295 g/t) for silver. A further 1.43 million gold equivalent ounces are
contained in inferred mineral resources of 1.03 million tons at a grade of
1.340 oz/ton (45.95 g/t) for gold and 2.72 oz/ton (93 g/t) for silver; gold
equivalent ounces in the estimated inferred resources increased 111% from June
2008.
    The resource estimate has benefited significantly from over nine months
of trial mining, which generated data from channel sampling and delineation
drilling for stope development. As a result of the integration of empirical
data from geological observations and ore control sampling into the vein
model, more stringent parameters have been applied to measured and indicated
classifications. In addition, 161 additional boreholes (totaling 51,430 feet)
completed in the period from April 2008 to March 31, 2009 were integrated into
the model. The drilling program, mostly conducted from underground, has
provided infill data to delineate stopes for trial mining, and significantly
improved our understanding of the lateral and vertical geological continuity
of the vein system. The resource estimate reflects depletion of material mined
in 2008 and 2009 (up to March 31 2009), totaling 103,746 gold equivalent
ounces at an average grade of 1.55 oz/ton.
    Results of the resource estimate based on all drilling and ore control
channel sampling to March 31, 2009 are tabulated below.

    
    -------------------------------------------------------------------------
                                                                   Contained
     Resource  Cut-off                            Au         Au        Au
     Category  oz/ton     Tons      Tonnes     oz/ton      g/t       oz(2)
    -------------------------------------------------------------------------
    Measured     0.25    199,300    180,800      1.895      64.98    377,700
    -------------------------------------------------------------------------
    Indicated    0.25    911,900    827,200      1.008      34.54    918,700
    -------------------------------------------------------------------------
    Total
     Measured &
     Indicated   0.25  1,111,200  1,008,000      1.167      40.00  1,296,400
    -------------------------------------------------------------------------
    Inferred     0.25  1,035,300    939,200      1.340      45.95  1,387,500
    -------------------------------------------------------------------------
    -------------------------------------------------------------------------


    ---------------------------------------------------
                                 Contained   Contained
    Resource      Ag       Ag        Ag          Au
     Category  oz/ton     g/t       oz(2)     eq oz(1)
    ---------------------------------------------------
    Measured    29.02      994.8  5,782,800    468,100
    ---------------------------------------------------
    Indicated    4.13      141.5  3,763,300    977,500
    ---------------------------------------------------
    Total
     Measured &
     Indicated   8.59      294.6  9,546,100  1,445,600
    ---------------------------------------------------
    Inferred     2.72       93.2  2,815,400  1,431,500
    ---------------------------------------------------
    ---------------------------------------------------

    (1) Gold equivalent ounces (Au eq oz) were calculated by using the
        following metal prices: US$800/oz for Au and US$12.5/oz for Ag.
    (2) Metallurgical recoveries are not applied to resource values.
        Contained metal estimates assume 100% recoveries.
    Some figures may not add due to rounding.

    The total estimated measured and indicated mineral resources prior the
depletion from trial mining was 1.549 million gold equivalent ounces and is
comparable with the 1.569 million gold equivalent ounces in 1.615 million tons
grading 0.87 oz/ton (29.71 g/t) Au and 4.57 oz/ton (156.68 g/t) Ag at a 0.25
oz/ton cut-off announced in June 2008.
    There are internal differences to the current and 2008 estimates, which
are mainly related to modifications to resource estimation procedures
described below:

    -   Empirical geological measurements have confirmed the previous model
        over estimated the width of the veins, hence, tons were over
        estimated tons but, at the same time, grade was under estimated. The
        current estimate utilises an improved method for modelling the veins
        (a mathematical algorithm with a minimum tolerance of a 6" vein
        width) and, coupled with a partial percentage estimate, has led to a
        higher accuracy in estimating the volume from the wire-frame model of
        the veins;

    -   Grade interpolation within the vein wire-frames was done using
        Inverse Distance Squared statistics in the current estimate (instead
        of Ordinary Kriging geo-statistics);

    -   Search radii utilized to categorize the confidence of grades within
        the vein wire-frames were decreased (100 feet/30 meters for measured
        and 280 feet/85 meters for indicated) and the average distance of
        informing samples was introduced, which increased the stringency for
        the measured and indicated categories; and

    -   The minimum number of samples to inform a given block was increased
        to 3 (compared to 2 in the previous estimate).
    

    The outcome of these changes is a more conservative approach to resource
classification that more closely reflects what is observed empirically
underground. Consequently, the tonnage in the measured category has decreased
but grade has increased. Tonnage in the indicated category has increased due
to reclassification and tonnage in the inferred category has increased due to
re-classification and additional drilling testing the extent of
mineralization.
    As the mine development progresses, the evaluation and upgrade of the
mineral resources from the inferred and indicated to a measured category will
provide data to assess the potential for reducing cut-off grade. Also the
current testing of various mining technologies may reduce stoping costs, and
expand the opportunity to exploit certain narrow veins that would otherwise
not be considered in the mine plan. Employing a lower cut-off grade would
allow lower grade material in the indicated category to be included in the
resource.
    The depth extent of the vein system is yet to be fully established,
therefore, to be conservative, inferred resources have been constrained to a
depth of 4,350 feet (1,318 meters) above mean sea level (approximately 1,200
feet or 380 meters below surface). Certain areas of previous indicated
resource have also been re-categorized into inferred because of lesser density
of sampling data. Inferred resource grades have increased from 0.510 oz/ton to
1.34 oz/ton for gold and 1.43 oz/ton to 2.72 oz/ton for silver due to the
localized extrapolation of well defined areas of higher grade pay shoots in
the measured and indicated categories. There is a noticeable decrease in
silver grades from measured to inferred categories which reflects the
occurrence of the Ag-selenide naumanite in the well drilled and sampled high
grade shoots as opposed to lesser borehole data in the inferred zones. The
lack of sample density in the inferred material underpins the lesser
confidence in the resources in this category.
    The ongoing program will continue to focus primarily on extensions of the
Gwenivere and Clementine vein system to the west/northwest and at depth. Also,
further investigation of Blanket zone mineralization hosted in Tertiary
volcanics above the Gwenivere/Clementine vein system is planned. Detailed
reassessment and modeling of all Blanket zone intersections is currently
underway, as there is potential for a significant resource in this area as
indicated by previous surface drilling. The Company currently has three drill
rigs in operation underground, undertaking stope delineation, resource infill
and exploration drilling. Surface exploration is currently focused on
collating and reviewing all geophysical, geological and drilling data for the
property, with the intent of better delineating basement structures that
control mineralisation. Additional drilling is also being considered for the
Hatter Graben area (press release January 29, 2009) during the third and
fourth quarters of 2009.
    Ferdi Dippenaar, President and CEO, commented:
    "Our ongoing exploration drilling programs and results from trial mining
continue to confirm the prospectivity of the Hollister property, evidenced in
the substantial increase in the reported resources. The tighter geological
controls constraining the estimate are also improving trial stope tonnage and
grade estimates and, as a consequence, our mine planning is benefiting from
more accurate information. As the underground development continues, there
will be further opportunities to drill test the depth extensions of a number
of high grade zones that are emerging from the evaluation. The continued
exploration drilling from underground is bearing success with tracking the
lateral extensions of the Hollister veins both eastward towards Hatter Graben,
but also stepping northwestward into the major Butte Fault bounding structure.
Furthermore, the review of Blanket style mineralization in the overlying
volcanics may provide an interesting upside to the current resource profile,
as it could be mined from the current infrastructure."
    The mineral resources reflect an in situ vein model, and tonnages and
grades were estimated by using a combination of a partial percentage block
model and constrained inverse distance statistics. There is no mining dilution
included within the vein model.
    The estimates were completed by Dale Richards, Pr.Sci.Nat., Great Basin
Gold's Group Mineral Resource Geologist, and signed off by Phil Bentley,
Pr.Sci.Nat., Great Basin Gold's Vice President: Geology & Exploration, a
Qualified Person as defined by Canadian Securities Regulations in National
Instrument 43-101, who has reviewed and approved the information and this news
release. Details of the estimate will be included in a technical report filed
on www.sedar.com in 45 days.

    
    Ferdi Dippenaar
    President and CEO

    -------------------------------------------------------------------------
    Samples collected from the Hollister Development Block 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.
    -------------------------------------------------------------------------

    No regulatory authority has approved or disapproved the information
    contained in this news release.
    

    This release includes certain statements that may be deemed
"forward-looking statements". All statements in this release, other than
statements of historical facts, that address possible future commercial
production, reserve potential, exploration drilling results, development,
feasibility or exploitation activities and events or developments that Great
Basin Gold expects to occur are forward-looking statements. Although the
Company believes the expectations expressed in such forward-looking statements
are based on reasonable assumptions, such statements are not guarantees of
future performance and actual results or developments may differ materially
from those in the forward-looking statements. Factors that could cause actual
results to differ materially from those in forward-looking statements include
market prices, exploitation and exploration successes, continuity of
mineralization, uncertainties related to the ability to obtain necessary
permits, licenses and title and delays due to third party opposition,
geopolitical uncertainty, changes in government policies regarding mining and
natural resource exploration and exploitation, and continued availability of
capital and financing, and general economic, market or business conditions.
Investors are cautioned that any such statements are not guarantees of future
performance and those actual results or developments may differ materially
from those projected in the forward-looking statements. For more information
on the Company, Investors should review the Company's annual Form 40-F filing
with the United States Securities and Exchange Commission and its home
jurisdiction filings that are available at www.sedar.com.

    
    Information Concerning Estimates of Measured, Indicated and Inferred
    Resources
    

    This news release also uses the terms "measured resources", "indicated
resources" and "inferred resources". The Company advises investors that
although these terms are recognized and required by Canadian regulations
(under National Instrument 43-101 Standards of Disclosure for Mineral
Projects), the U.S. Securities and Exchange Commission does not recognize
them. Investors are cautioned not to assume that any part or all of the
mineral deposits in these categories will ever be converted into reserves. In
addition, 'inferred resources' have a great amount of uncertainty as to their
existence, and economic and legal feasibility. It cannot be assumed that all
or any part of an Inferred Mineral Resource will ever be upgraded to a higher
category. Under Canadian rules, estimates of Inferred Mineral Resources may
not form the basis of feasibility or pre-feasibility studies, or economic
studies except for Preliminary Assessment as defined under 43-101. Investors
are cautioned not to assume that part or all of an inferred resource exists,
or is economically or legally mineable.





For further information:

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; Melanee Henderson in North America 1-800-667-2114; Barbara
Cano at Breakstone Group in the USA (646) 452-2334

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