Rubicon Announces Amended Inferred Mineral Resource and Geological Potential Estimates for Phoenix Gold Project, Red Lake Ontario
TORONTO, March 31 /CNW/ --
TSX:RMX | NYSE AMEX:RBY March 31, 2011
TORONTO, March 31 /CNW/ - Rubicon Minerals Corporation (RMX: TSX) (NYSE-AMEX: RBY) (the 'Company' or 'Rubicon') announced
amended inferred mineral resource and geological potential estimates
today for its Phoenix Gold Project, F2 Gold System. The amended
estimates are a result of the previously announced review by the
British Columbia Securities Commission of the Company's NI 43-101
technical report filed on January 11, 2011 (the 'Report').
The following amended estimates were prepared by Peter George of Geoex
Limited, the Company's independent QP and author of the Report (the
'Author'), and are effective March 31, 2011:
1. Amended Inferred Mineral Resource Estimate
Polygonal Model Inferred Mineral Resource Estimate - Uncapped and
Capped
_____________________________________________________________________
| Polygonal Model Inferred Mineral Resource Estimate |
| (5 g/t gold cut-off and 10 gram x metre product (core length) - |
| surface to 1200 metres below surface) |
|_____________________________________________________________________|
| | Gold (Uncapped Grade) |10-5-2 oz Capped Gold Grade* |
| |_______________________|_____________________________|
| |Inferred gold| | | |
| | grade |Inferred |Inferred gold grade|Inferred |
|Inferred Tonnes| (g/t) | Ounces | (g/t) | Ounces |
|_______________|_____________|_________|___________________|_________|
| 5,500,000 | 20.34 |3,597,000| 17.29 |3,057,000|
|_______________|_____________|_________|___________________|_________|
The polygonal model inferred resource estimate is based on composites
which satisfy a 5 g/t gold cut-off and 10 gram x metre product (core
length) as at July 31, 2010.
The estimates are in-situ and undiluted and figures are rounded.
*10-5-2 refers to an empirical capping strategy that caps gold values
greater than 10 oz/ton to 10 oz/ton (342.8g/t), those between 5 and 10
oz/ton to 5 oz/ton (171.4 g/t), those between 2 and 5 oz/ton to 2
oz/ton (68.6 g/t). Values less than 2oz/ton remain uncapped.
The polygonal model inferred mineral resource estimate prepared by the
Author was based on 166,886 metres of diamond drilling in 237 drill
holes carried out between February 27, 2008 (the date of the initial
discovery) and July 31, 2010. The above inferred mineral resource
estimate was prepared using the polygonal calculation method (see
'Resource Calculation Methodology' below for details) which, in the
opinion of the Author, is the appropriate method and is typically used
for this type of deposit. The cut-off used is considered to be an
economically reasonable estimate of breakeven mining costs.
Inferred resources are too speculative to have economic consideration
applied to them and there is no certainty that the inferred resources
will be converted to measured and indicated resources.
2. Amended Block Model Validation Inferred Mineral Resource Estimate
In addition to the polygonal model mineral resource calculation, as a
means of validating the inferred mineral resource estimate by an
independent method, a block model was calculated utilizing Surpac
software.
Block Model Validation Inferred Mineral Resource Estimate (5 g/t
cut-off) (surface to 1200 metres below surface)
_________________________________________________________________
| | Uncapped block |10-5-2 oz Capped block |
| | model estimate | model estimate* |
| |______________________________|________________________|
|Inferred |Inferred gold |Inferred Ounces|Inferred gold |Inferred |
| Tonnes | grade (g/t) | | grade (g/t) | Ounces |
|_________|______________|_______________|______________|_________|
|6,017,000| 16.49 | 3,190,000 | 15.69 |3,035,000|
|_________|______________|_______________|______________|_________|
The block model inferred mineral resource estimate is based on
composites which satisfy a 5 g/t gold cut-off as at July 31, 2010.
The estimates are in-situ and undiluted and figures are rounded.
*10-5-2 refers to an empirical capping strategy that caps gold values
greater than 10 oz/ton to 10 oz/ton, those between 5 and 10 oz/ton to 5
oz/ton, those between 2 and 5 oz/ton to 2 oz/ton. Values less than
2oz/ton remain uncapped.
The block model inferred mineral resource estimate prepared by the
Author was based on 166,886 metres of diamond drilling in 237 drill
holes carried out between February 27, 2008 (the date of the initial
discovery) and July 31, 2010. The cut-off used is considered to be an
economically reasonable estimate of breakeven mining costs.
Inferred resources are too speculative to have economic consideration
applied to them and there is no certainty that the inferred resources
will be converted to measured and indicated resources.
Parameters selected for the block model validation inferred mineral
resource estimate are detailed below under 'Resource Calculation
Methodology'. On an uncapped basis, the block model estimates are
within 9.4% of the tonnage, 18.9% of the grade and 11.3% of the total
contained ounces of the uncapped polygonal estimate. On a capped basis,
the block model estimates are within 9.4% of the tonnage, 9.3% of the
grade and 0.7% of the total contained ounces of the capped polygonal
estimate. While the Author does not consider the block model the most
appropriate method for this type of deposit, the results provide strong
supporting validation for the preferred polygonal estimate reported
above. Capping has been carried out to allow an evaluation of the
effect of capping. As additional data becomes available, additional
studies of statistically based capping may be required.
3. Amended Geological Potential
In addition to the above referenced inferred mineral resource estimates,
the Author carried out a re-evaluation of geological potential between
0 and 1500 metres below surface, based on an analysis of the
distribution of current drilling (strike length of 898 metres as of
July 31, 2010) and opportunity for infill and expansion drilling to
depth. The system remains open along strike and to depth beyond the
current limit of drilling.
The geological potential is based on the projection and extrapolation of
the inferred resource present between 0 to 500 metres below surface as
this area has the highest drill density of one drill hole per 55 m(2) and contains an inferred resource of 2,988,000 tonnes grading 26.55 g/t
gold containing 2,550,000 ounces of gold. In a portion of the area
between 500 and 1500 metres below surface, drilling density is lower
but still sufficient to qualify resources where drilling has been
carried out. In the opinion of the Author, based on a review of project
data, experience from elsewhere in Red Lake and general observations on
lode gold deposits, the grade and tonnage profile of the area above 500
metres is likely to be replicated to depth with additional drilling.
The Author estimates exclusive of the inferred resources, geological
potential on a uncapped basis of between 1,670,000 and 4,360,000 tonnes
grading 21.2 to 29.2 g/t gold for an additional 1,300,000 to 5,600,000
ounces of gold. If the 10-5-2 capping described above were applied,
these estimates of potential would be reduced to 800,000 to 4,300,000
ounces of gold grading between 16.9 g/t and 23.2 g/t gold. A 10% upside
and 20% downside potential for both tonnes and grade has been
incorporated to address the possible uncertainty of the geological
potential estimate.
The potential tonnages, grades and ounces set forth in the analysis of
geological potential are conceptual in nature, as there has been
insufficient exploration to define a mineral resource and it is
uncertain if further exploration will result in the target being
delineated as a mineral resource. Potential estimates are separate
from the inferred mineral resources stated above.
The final amended NI 43-101 compliant technical report containing the
amended inferred mineral resource and geological potential estimates
will be filed on SEDAR within 14 days.
The principal differences between the amended estimates and those
contained in the Report are as follows:
The polygonal inferred mineral resource estimate was revised to
(1) include resources between 0 and 1200 metres below surface
(originally 0 to 1500 metres). Changes are tabulated below:
Amended Polygonal Inferred Mineral Resource Estimate, March 31,
2011
__________________________________________________________________
|Uncapped (0 -1200 metres below|10-5-2 Capped (0-1200 metres below|
| surface) | surface) |
|______________________________|__________________________________|
| Tonnes |Au g/t| Ounces | Tonnes |Au g/t| Ounces |
|_________|______|_____________|_________|______|_________________|
|5,500,000|20.34 | 3,597,000 |5,500,000|17.29 | 3,057,000 |
|_________|______|_____________|_________|______|__________________|
Initial Polygonal Inferred Mineral Resource Estimate, January 11, 2011
Technical Report
_______________________________________
|Uncapped (0 -1500 metres below surface)|
|_______________________________________|
| Tonnes |Au g/t| Ounces |
|_________|______|______________________|
|6,204,000| 20.1 | 4,007,400 |
|_________|______|______________________|
Difference in Estimates
______________________________
|Uncapped (Initial vs. Amended)|
|______________________________|
|Tonnes |Au g/t| Ounces |
|_______|______|_______________|
|703,000| 0.24 | 410,000 |
|_______|______|_______________|
Block Model estimates were revised to reflect estimates between 0
(2) and 1200 metres below surface (originally 0-1500 metres below
surface) and capping was applied. Changes are tabulated below:
Amended Block Model Validation Inferred Mineral Resource Estimate
__________________________________________________________
|Uncapped (0 - 1200 metres)|10-5-2 Capped (0 - 1200 metres)|
|__________________________|_______________________________|
| Tonnes |Au g/t| Ounces | Tonnes |Au g/t| Ounces |
|_________|______|_________|_________|______|______________|
|6,017,000|16.49 |3,190,000|6,017,000|15.69 | 3,035,000 |
|_________|______|_________|_________|______|______________|
Initial Block Model Validation Inferred Mineral Resource
Estimate
_______________________________________
|Uncapped (0 -1500 metres below surface)|
|_______________________________________|
| Tonnes |Au g/t| Ounces |
|_________|______|______________________|
|5,830,000|17.17 | 3,210,000 |
|_________|______|______________________|
Difference in Estimates
______________________________
|Uncapped (Initial vs. Amended)|
|______________________________|
|Tonnes |Au g/t| Ounces |
|_______|______|_______________|
|187,000| 0.68 | 19,700 |
|_______|______|_______________|
(3) Geological Potential is now limited to between 0 and 1500 metres
below surface (previously 0 - 2500 metres below surface) and
results in the changes described above under 'Amended Geological
Potential'.
(4) The Author has clarified his reliance on the 5 g/t gold cut-off
and has removed tables in the Report regarding a 3 g/t gold
cut-off resource estimate.
(5) The Author has removed certain polygons which are below 1.2 metre
horizontal width although most of these are close to other data
points that could justify inclusion with some additional
drilling. This results in a reduction in tonnes of 8.1%, grade
increases by 4.5% and total ounces decrease by 4.0% compared to
the initial statement of uncapped polygonal inferred resource
estimate.
David Adamson, President and CEO of Rubicon, stated: 'We appreciate the
input the British Columbia Securities Commission has provided and
especially wish to thank our shareholders for their patience and
support during this period. All of us on the Rubicon team are pleased
that the amended estimates confirm the fundamental and material nature,
aspects and integrity of the mineral resource and look forward to
moving the Project forward.'
Resource Calculation Methodology
The construction of the polygonal and block models was a product of
collaboration between Rubicon and Geoex. Rubicon personnel included
Matt Wunder P.Geo, V.P. Exploration and Eric Hinton P.Eng., Project
Manager. All data in the resource evaluation were reviewed by Geoex
with Mr. Peter George of Geoex assuming responsibility for the resource
and geological potential estimates upon which the statements reported
herein are based.
Polygonal Resource calculation
Geological sections and plans at scales of 1:1000, 1:500 and 1:200 were
reviewed by the Author. These plans and sections included a set of
geological sections that were generated and interpreted by an
independent geological consultant. Sections were selected at a tight
spacing of 20 metres through the F2 Gold System and were based on all
available geological and assay information. They show that major rock
types can be correlated on section to depths of 1500 metres and over a
strike length of approximately 1200 metres. The Author reviewed
selected drill core from the F2 Gold System, reviewed geological
logging and sampling protocols used by project staff and agrees with
the geological interpretation derived from the geological sections.
Gold mineralization ranging from low (>1 g/t) to high grade is observed
within (i.e. is bounded by) major mapped geological units. As described
above, the geological sequence is sub-vertical to steep west dipping.
The QAQC protocols of the Company have been independently reviewed and
approved by a third party consultant. The Company also had an
independent third party consultant audit the composite calculations.
The Author is of the opinion that the database underlying the Geoex
resource estimates is suitable.
The Author prepared both 3g/t and 5g/t assay composites tables in 3D
AutoCad to allow inspection of the distribution of significant gold
mineralized intervals excluding a large number (>4000) lower grade
intercepts (>1 g/t gold). Significant drill intersections within
bounding geological units and mineralized sub-zones were observed to
conform closely to bounding geological units and are largely aligned in
the direction of the East Bay Deformation Zone ('EBDZ'), i.e. they
display a northeast trend and sub-vertical to steep westerly dip.
The Author has selected an elliptical area of influence with a minor
axis radius of 37.5 metres and a major axis radius of 75 metres with
the major axis plunging steeply to the south parallel to the local and
regional structural plunge. The dimensions reflect distances that are
well within the observed horizontal and vertical dimensions and
continuity of the known mineralization.
The area of each polygon was determined in 3D AutoCad. The horizontal
width of the polygon perpendicular to the plane of the intersection was
calculated in the resource spreadsheet based upon the core width, the
dip and azimuth of the hole at the long section pierce point and the
strike direction of the long section. The volume of the polygon was
determined by multiplying the area from the vertical section by the
horizontal width at the pierce point on the long section. Tonnage is
calculated by multiplying the volume of the polygon (cubic metres) by
the average specific gravity (2.85 assumed for this amended resource
estimate). Average grade is estimated by the weighted average of the
sum of the polygon tonnes x grade divided by the total tonnes.
Block Model calculation
In order to validate the polygonal model, the Author reviewed the
results of a second inferred mineral resource estimate derived using
block model analysis. The block model was prepared using Surpac Version
6.1.4 software as follows:
The block model estimation was performed using the same data set used
for the polygonal resource estimate. Drill hole assay data were
reviewed and a composite interval of 1.0 metre was selected for the
data set. During the compositing process, Surpac software declustered
the data to address uneven spatial assay distribution. Variogram
analysis was performed and block size optimization was carried out.
Verification of Surpac block model assumptions, variogram analysis and
input parameters was carried out by an independent third party.
The results of the variogram analysis are as follows:
Variogram parameters
• Major axis (dip
direction - near vertical): 36.0m radius
Anisotropy Ratios
• Semi major axis 1.40 (ratio to major axis) or
(strike direction): 25.7m radius
• Minor axis (across 3.40 (ratio to major axis) or
strike direction): 10.6m radius
Search ellipse parameters
• First Axis (strike
direction): 13.40 degrees (Mine Grid)*
• Second Axis (plunge
direction): 69.00 degrees
• Third Axis (dip
direction): 10.00 degrees
• Inferred resource estimate used search parameters of 2
times variogram ranges
• Max search distance of
major axis: 72.000 metres
*Mine Grid zero degrees azimuth = 45 degrees clockwise rotation to
magnetic North.
The variogram results are generally consistent with the geological model
used in the polygonal estimation having two axes that approximate the
observed geological and mineralized trend of the EBDZ (northeast). The
plunge of the second axis is also generally consistent with the
observed plunge in the geological model (70-80 degrees) used in the
polygonal estimate.
Block Model Validation Inferred Mineral Resource
The block size selected for the block model was based on a block size
optimization analysis performed using Surpac. The search method
selected was inverse distance squared. The search radius employed was
two times the variogram ranges (72 x 51 x 21 metres) and is consistent
with standard block model methodology for inferred mineral resources.
A minimum of three samples and maximum of five samples were selected as
requirements for populating each block.
It is noted that the standard 2x variogram search parameter dimensions
used to classify the block model inferred resource are larger than the
polygons used in the polygonal estimate derived from analysis of
sectional data which lends independent support to the polygon size
selected in the polygon model which was derived independently from
analysis of sectional geological and assay data.
The block model was constrained utilizing surfaces for the following:
-- The lake bottom;
-- The claim boundary; and
-- The hanging wall geological contact to the F2 system.
The Author evaluated the effect of using the smaller polygonal search
ellipse instead of the the 2 times variogram range which resulted in no
material difference to the stated block model inferred mineral resource
estimate.
RUBICON MINERALS CORPORATION
'David W. Adamson'
President & CEO
Mineral Resources
Mineral resources that are not mineral reserves do not have demonstrated economic
viability. The estimate of mineral resources may be materially affected
by environmental, permitting, legal, title, taxation, socio-political,
marketing, or other relevant issues. The quantity and grade of reported
inferred resources in this estimation are uncertain in nature and there
has been insufficient exploration to define these inferred resources as
an indicated or measured mineral resource and it is uncertain if
further exploration will result in upgrading them to an indicated or
measured mineral resource category. The mineral resources in this press
release were estimated using CIM Standards.
Qualified Persons
The content of this news release has been read and approved by Peter George, P.Geo.
President and consulting geologist of Geoex Limited, an independent
Qualified Person as defined by NI 43-101. Exploration drill programs
and all data forming the basis of the inferred resource estimate
described in this release were supervised and verified by Terry Bursey,
P.Geo,. Regional Manager for Rubicon and a Qualified Person as defined
by NI 43-101. All data required for the block calculation described in
this release was prepared and verified by Eric Hinton, P.Eng, Project
Manager of Rubicon and a Qualified Person as defined by NI 43-101. The
inferred resource estimate, including the polygonal resource
calculation and the block model calculation, and the geological
potential analysis were prepared by Peter George, P.Geo., President and
consulting geologist of Geoex Limited, an independent Qualified Person
as defined by NI 43-101, and he verified all data received from Rubicon
in connection with same.
Cautionary Note to U.S. Readers Regarding Estimates of Measured, Indicated and Inferred
Resources
This press release uses the term 'inferred resources.' We advise U.S. investors that
while this term is recognized and required by Canadian regulations, it
is not recognized by the SEC. 'Inferred resources' have a great amount
of uncertainty as to their existence, and great uncertainty as to their
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 a feasibility study or
prefeasibility studies, except in rare cases. The SEC normally only
permits issuers to report mineralization that does not constitute
'reserves' as in-place tonnage and grade without reference to unit
measures. U.S. investors are cautioned not to assume that any part or all of a
measured, indicated or inferred resource exists or is economically or
legally mineable.
Forward Looking Statements
This news release contains statements that constitute 'forward-looking
statements' within the meaning of Section 21E of the United States
Securities Exchange Act of 1934 and 'forward looking information'
within the meaning of applicable Canadian provincial securities
legislation (collectively, 'forward-looking statements') .
Forward-looking statements often, but not always, are identified by the
use of words such as 'seek', 'anticipate', 'believe', 'plan',
'estimate', 'expect', 'targeting' and 'intend' and statements that an
event or result 'may', 'will', 'should', 'could', or 'might' occur or
be achieved and other similar expressions. Forward-looking statements
in this document include statements regarding estimates of mineral
resources, estimates of gold grades and in-place ounces, the
preparation and timing of a final amended technical report in respect
of the inferred resource and geological potential estimates and the
timing and nature of future exploration programs. Our exploration
programs are dependent on projections which may change as drilling
continues, or if unexpected ground conditions are encountered. In
addition, areas of exploration potential are identified which will
require substantial drilling to determine whether or not they contain
similar mineralization to areas which have been explored in more
detail. The description of the extent of mineralized zones is not
intended to imply that any economically mineable estimate of reserves
or resources exists on the Phoenix project. Similarly, although
geological features of the F2 Gold System are interpreted to show
similarities to nearby gold producing mines owned by third parties,
this should not be interpreted to mean that the F2 Gold System has, or
that it will generate similar reserves or resources. Significant
additional drilling is required at F2 to fully understand system size
before a meaningful resource calculation can be completed.
The forward-looking statements that are contained in this news release
are based on various assumptions and estimates by Rubicon and involve a
number of risks and uncertainties. As a consequence, actual results
might differ materially from results forecast or suggested in these
forward-looking statements. Forward-looking statements involve known
and unknown risks, uncertainties, assumptions and other factors that
may cause the actual results, performance or achievements of Rubicon to
be materially different from any future results, performance or
achievements expressed or implied by the forward-looking statements.
Factors that could cause the actual results to differ include; risks
relating to fluctuations in the price of gold; the inherently hazardous
nature of mining-related activities; uncertainties concerning reserve
and resource estimates; results of exploration, availability of capital
and financing on acceptable terms, inability to obtain required
regulatory approvals, unanticipated difficulties or costs in any
rehabilitation which may be necessary, market conditions and general
business, economic, competitive, political and social conditions. These
statements are based on a number of assumptions, including assumptions
regarding general market conditions, timing and receipt of regulatory
approvals, the ability of Rubicon and other relevant parties to satisfy
regulatory requirements, the availability of financing for proposed
transactions and programs on reasonable terms and the ability of
third-party service providers to deliver services in a timely manner.
Although Rubicon has attempted to identify important factors that could
cause actual results to differ materially from those expressed or
implied in forward-looking statements, there may be other factors which
cause actual results to differ. Forward-looking statements contained
herein are made as of the date of this news release and Rubicon
disclaims any obligation to update any forward-looking statements,
whether as a result of new information, future events or results or
otherwise, except as required by applicable securities laws. There can
be no assurance that forward-looking statements will prove to be
accurate, as actual results and future events could differ materially
from those anticipated in such statements. Accordingly, readers should
not place undue reliance on forward-looking statements.
The Toronto Stock Exchange has not reviewed and does not accept
responsibility for the adequacy or accuracy of this release.
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Bill Cavalluzzo
VP-Investor Relations
1-866-365-4706