Resource Statement
25 November 2002 - 9:00AM
UK Regulatory
RNS Number:1945E
Griffin Mining Ld
25 November 2002
GRIFFIN MINING LIMITED
1 Berkeley Street, London, W1J 8DJ, United Kingdom
Telephone: + 44 (0)20 7016 8821 Facsimile: + 44 (0)20 7016 9124
E mail: griffin@griffinmining.com
25th November 2002
NEW RESOURCE STATEMENT FOR CAIJIAYING PROJECT
EXCEEDS EXPECTATIONS
Griffin Mining Limited ("Griffin" or the "Company") has today published new
resource estimates for its Caijiaying zinc-gold project compiled by independent
consultants Micromine Pty Ltd Consulting Division ("Micromine") in accordance
with the guidelines set out in the Australian Code for Reporting of Mineral
Resources and Ore Reserves (The JORC Code). A summary report written by
independent geological consultants CSA Australia Pty Ltd on the new resource
estimates is attached hereto.
The results exceed all the expectations of the Company with 61/2 times the
previously estimated contained metal now identified in the Caijiaying deposit
rising from 190,000 tonnes to 1,230,000 tonnes of contained zinc metal.
ZINC
Ignoring the associated base and precious metals:
At a 4% zinc cut-off the project now hosts an:
* indicated resource of 16.9 million tonnes @ 7.84% Zinc; and
* inferred resource of 6.68 million tonnes @ 8.69% Zinc;
for a Total Resource of 23.6 million tonnes @ 8.08% Zinc.
This compares to the previously announced total resource of 2.6 million tonnes @
9.12% Zinc at a 4% zinc cut-off
At a 7% zinc cut-off the project now hosts an:
* indicated resource of 6.95 million tonnes @ 11.58% Zinc;
and
* inferred resource of 3.602 million tonnes @ 11.73% Zinc;
for a Total Resource of 10.56 million tonnes @ 11.63% Zinc.
This compares to the previously announced total resource of 1.52 million tonnes
@ 12.34% zinc at a 7% zinc cut-off
The new resource estimates cover only zone III at Caijiaying. The new lode
orientations are consistent with mineralisation at the zone II deposit, which
is situated (within Griffin's licence area) 1 kilometre to the south of the main
zone III deposit. This strongly suggests that the two deposits are continuous
opening up a large area for further exploration once production begins at
Caijiaying.
GOLD
The diamond drilling programme undertaken by Griffin in the summer of 2002
encountered significant gold intercepts which taken together with earlier gold
results, suggest that a distinct part of the overall deposit may have potential
as a separate gold resource. In order to gain an impression of the size of this
potential gold resource, Micromine compiled separate estimates for the gold
resource at zone III of:
2.61 million tonnes at 6.78 g/t at a 3% gold cut off.
1.675 million tonnes at 8.63 g/t at a 4% gold cut off.
1.265 million tonnes at 9.99 g/t at a 5% gold cut off.
This places over 500,000 ounces of gold at Caijiaying at a 3% gold cut off.
As these estimates are based only on partial gold analyses and because the
drill-hole spacing is very wide for estimating gold mineralisation, the gold
resource is categorised as inferred.
FUTURE
Griffin is now completing a fully bankable feasibility study with a view to
raising the necessary project finance and the commissioning of an underground
mine at Caijiaying at the earliest opportunity.
Mladen Ninkov, Chairman, commenting on the resource estimate said:
"This is one of those rare circumstances when a Chairman of a mining company
doesn't need to say anything further. The new resource model, compiled by
independent consultants in accordance with the guidelines set out in the JORC
Code, speaks well and truly for itself. It is an amazing result and confirms
the belief management has always held that Caijiaying is a world class mineral
field. I am delighted for our shareholders."
The Company acknowledges the continuing outstanding contribution of CSA
Australia Pty Ltd to Griffin and in relation to the Caijiaying area, and in this
instance, for their outstanding efforts in identifying, analysing and completing
a new geological interpretation of the mineralised structures at Caijiaying.
Further information
Mladen Ninkov - Chairman Telephone: +44(0)20 7016 8821
Roger Goodwin - Finance Director Telephone: +44(0)20 7016 8821
Charles Dampney - Charles Stanley Telephone: +44(0)20 7739 8200
Griffin Mining Limited's shares are quoted on the Alternative Investment Market
(AIM) of the London Stock Exchange (symbol GFM).
The Company's news releases are available on the Company's web site:
www.griffinmining.com
CSA Australia Pty Ltd
Geological Consultants
A.C.N 077 165 532
Level 1
47 Burswood Road
Burswood
Western Australia 6100
Telephone: +61 8 9355 1677
Facsimile: +61 8 9355 1977
Date; 22-Nov-02
Ref; RC.94.02
The Directors
Griffin Mining Ltd
1 Berekeley Street
London W1J 8DJ
United Kingdom
Re; The Caijiaying Project - New Resource Estimate
Dear Sirs,
I have pleasure in reporting the results of the new resource estimates for the
Caijiaying Zone III deposit which have been prepared according to your
instructions and following the receipt of the previously reported drilling
results and the generation of a new geological model.
Background
The previous two announcements reported the results of the pre-development
drilling program completed during last summer at Caijiaying and contained the
following information:
* The geological conclusions drawn from the drill results were that the
mineralisation at Caijiaying was contained within a series of steep (75 - 80
degrees) westerly dipping, variably mineralized envelopes. It will be
remembered that the orientation of these lodes was shown to be
north-northeast in contrast to the east-west orientation used in previous
Chinese studies.
* The assay results from the drilling program confirmed the initial visual
interpretations and the definition of the north-northeast, westerly dipping
lodes.
These data were compiled and incorporated into a new resource model by
independent resource consultants Micromine Pty Ltd Consulting Division who have
now released the results. The estimate has been completed by Mr Dmitry Pertel
MSc, AIG, AIE and Mr Alex Belous PhD under the guidelines of the Australasian
Institute of Mining and Metallurgy JORC Code, September, 1999. Mr Dean O'Keefe
BSc , MAusIMM, AIE conducted an on-site due diligence check of the core library
and drilling and sampling procedures. Mr Alex Belous PhD completed a due
diligence assessment of the Analabs laboratory in Perth, where the drilling
samples were analysed. Messrs Pertel and Belous conducted the resource computer
modelling with assistance from Project Geologist Mr Warren Woodhouse BSc (Hons),
MAusIMM from CSA.
Procedure
CSA Australia undertook the first part of the resource modelling exercise by
completing a new geological interpretation of the mineralised structures. It
was found that the lode geometry defined by the 2002 drilling program could be
extrapolated throughout the Zone III deposit area. This allowed nearly all the
previous Chinese intersections to be re-interpreted within a set of structural
envelopes that parallel the steep westerly dipping lodes defined by the summer
drilling program. A total of seven major sub-parallel north-northeast striking
envelopes were defined with only minor disruption caused by late cross-faults
and dykes. The boundaries of these envelopes were defined as the edges of
variably mineralised and altered zones. In several parts, a distinct hangingwall
and footwall lode was identified. However, in general, the mineralisation
within the envelopes is irregular and follows discontinuities in the host rocks
(as was shown by the trial mining) and is therefore more suitable for estimation
by computer rather than manual techniques.
The boundaries for each mineralised envelope were first interpreted in
longitudinal section and then in cross section before being digitized into
Micromine software. Barren cross-cutting porphyry dykes, the overlying Jurassic
sequence and the transported Mongolian sand cover were also interpreted in
section and digitized into Micromine in order to remove waste from the model.
From the digitized mineralized envelopes a series of wireframes were constructed
with the assistance of Micromine personnel. These wireframes were checked in 3D
and corrected as necessary before modelling was carrying out.
The entire Zone III drill-hole database was used in the modelling process. The
database comprises a total of 79,472m of diamond core with 12,993 analyses for
zinc and 7,586 for gold. Early Chinese samples were collected by splitting the
diamond drill core and analyzing by a colorimetric method. Later drill sampling
by western companies (including Griffin) consisted of cutting drill core and
analyzing the core using both Australian and Chinese laboratories. Cross
checking of samples was carried out using a second Australian laboratory.
Micromine conducted variogram analysis within the mineralised wireframes to
provide the search and grade interpolation parameters for the resource
estimation. Both Ordinary Kriging and Inverse-Distance Weighting (to the
squared power) methods were then used with various search parameters. The
Inverse Distance Weighting method was used as a check to the preferred Ordinary
Kriging Method. A sensitivity analysis with a total of seven models was run
with results plotted and cross checked against the geological interpretation
until a "best fit" was obtained. The resource category was defined by the search
parameters as determined from the variogram analysis, the number of samples and
holes used in the calculation of a block grade.
Resource Estimate Results
The results of the Micromine resource estimate are presented in Table 1 at
various minimum cut-off grades. The wide range of cut-off grades shown is
because the first-stage mine is planned to be a relatively small-scale, high
grade operation at a 7 - 8% zinc cutoff (depending on final economic factors).
However, more conventional lower cut-off grades are also shown in the 4 - 6%
range for comparison. These would be more likely to apply if the operation is
scaled up at a later stage (depending on scale of operation and zinc price - see
below).
Table 1. Caijiaying Zone III Total Resource at various cut-off grades
Zn Cut Off, Category Tonnes, Mt Volume, m3 Zn, % Pb, % Ag, g/t Au, g/t
%
4 Indicated 16.905 5.535 7.84 0.33 31.19 0.75
Inferred 6.675 2.173 8.69 0.46 30.32 0.50
Total: 23.581 7.708 8.08 0.37 30.94 0.68
5 Indicated 12.282 3.989 9.11 0.37 35.79 0.76
Inferred 5.015 1.618 10.10 0.52 33.29 0.48
Total: 17.297 5.607 9.40 0.42 35.07 0.68
6 Indicated 9.233 2.975 10.32 0.40 39.96 0.72
Inferred 4.252 1.364 10.93 0.56 35.50 0.48
Total: 13.485 4.340 10.51 0.45 38.55 0.64
7 Indicated 6.953 2.223 11.58 0.43 42.85 0.64
Inferred 3.602 1.150 11.73 0.60 37.24 0.49
Total: 10.555 3.373 11.63 0.49 40.94 0.59
7.5 Indicated 6.100 1.943 12.18 0.45 44.82 0.60
Inferred 3.345 1.065 12.08 0.62 38.18 0.48
Total: 9.445 3.008 12.14 0.51 42.47 0.56
8.5 Indicated 4.784 1.512 13.34 0.46 47.34 0.52
Inferred 2.820 0.894 12.83 0.62 38.83 0.48
Total: 7.605 2.406 13.15 0.52 44.18 0.50
9 Indicated 4.179 1.316 14.01 0.45 48.07 0.49
Inferred 2.548 0.805 13.27 0.62 38.88 0.48
Total: 6.727 2.121 13.73 0.51 44.59 0.49
10 Indicated 3.233 1.009 15.33 0.45 50.99 0.46
Inferred 1.909 0.599 14.50 0.58 38.67 0.47
Total: 5.142 1.608 15.02 0.50 46.42 0.46
Comparison with previous estimates
The new resource estimate represents a 6.5 times increase in contained metal
compared to the previous estimate at the same cut off (1.23Mt compared to 0.19Mt
of zinc metal). The previous estimate was based on extrapolating the thickness
of mineralization in the underground trial mining to the rest of the deposit
area. Once the geometry of the Chinese model was found to be incorrect, the
resource could not be re-modeled reliability until a viable geological model
could be demonstrated. The previously announced estimate was 1.52Mt @ 12.34%
zinc, 0.53% lead, 48g/t silver and 0.75g/t gold at a 7% zinc cut-off.
Other items of significance
As an indication of the reliability of the new resource model, Micromine were
asked to separately estimate the northern part of the deposit which included the
recent east-west cross drilling, both with the new results and without them.
The results of each run were within 3% of one another, which gives confidence
that the new geological interpretation is correct.
In the last announcement, attention was drawn to the possibility that a distinct
part of the deposit may contain a gold resource which could be mined for
separate processing. In order estimate this potential, Micromine was requested
to run a gold estimate on the entire deposit within the zinc envelopes. It
should be borne in mind that this estimate includes the gold in the zinc-rich
mineralisation reported above and is based on only partial gold analyses as not
all core samples have been analyzed for gold. Because of this, and also because
the drill-hole spacing is very wide for estimating gold mineralisation, the
resource is placed in the Inferred category. The results are shown in Table 2.
Table 2. Caijiaying Zone III Inferred Gold Resource at various cut-off grades
Gold Cut-Off in g/t Tonnes Grade in g/t Au
Au
3 2,610,000 6.78
4 1,675,000 8.63
5 1,265,000 9.99
Conclusions
* The new geological interpretation of the summer drilling results has at
last enabled the Caijiaying mineralisation to be reliably modeled.
* The new resource estimate that is based on the revised geological model
has exceeded expectations and is 6.5 times the amount of contained zinc
metal than the last reported estimate.
* The size of the new resource estimate means that work on project mine
planning can now proceed with confidence.
* The previously proposed first stage, high-grade mine plan of a 180,000
tonnes per annum operation is still recommended as a first-stage choice as
it will take time to develop the underground decline and mine headings.
* The size of the new resource estimate gives considerable confidence that
the mine throughput can be increased once the mine is sufficiently
developed.
* The size of the initial Inferred gold resource confirms that there is
potential to also develop a separate gold recovery operation within the
larger Zone III mine as a further upgrade to the project. This will best be
defined by infill underground exploration from the zinc-mine decline.
* The new resource model has also suggested that the Zone III mineralisation
may continue a further 1km to the south and link up with the previously
sub-economic Zone II deposit. If future exploration proves this to be the
case, it will allow the option of further upgrades to the operation or a
longer mine life. It is also believed that there is good potential for
further gold discoveries in the area.
Neither CSA nor Micromine Consulting nor any of their staff have any beneficial
interest in Griffin other than the provision of ongoing professional fee-paying
services.
Signed
_______________________
Rupert W. A. Crowe
BSc, F.AusIMM, MIAEG
Managing Director, CSA Australia Pty Ltd
This information is provided by RNS
The company news service from the London Stock Exchange
END
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