‰ output from the Mincom geological model was reviewed for accuracy in relation to the available drilling data,
‰ typical cross-sections across the pits, and ‰ coal quality database plans and tabulations.
In summary, the database is of an adequate standard and the work has been undertaken by competent professionals. A copy of the model was provided to MMC and MMC is of the opinion that the geological model
is of sufficient accuracy to be used for Coal Resource estimation. There are no fatal flaws identified, however the following observations are made in relation to the level of confidence of the database and model:
‰ thin seam interpretation is of lower confidence than for thicker seams due to the use of “touch” coring and the absence of geophysical logging, and
‰ the lack of supporting geophysical logging data lowers the overall level of confidence in the database and model such that the Coal Resource estimates can only be of maximum Indicated status.
4.5 Geological Confidence And Resource Categories
Open-cut Geological Resources are defined as that part of the identified in-situ coal “with reasonable prospects for eventual economic extraction” JORC Code, 2004.
The JORC Code identifies three levels of confidence in the reporting of resource categories as follow: ‰ Measured—“that part of a Mineral Resource for which the tonnage, densities, shape, physical
characteristics, grade and mineral content can be estimated with a high level of confidence
”. Note: bolding added by MMC.
‰ Indicated—“...estimated with a reasonable level of confidence”. ‰ Inferred—“…estimated with a low level of confidence”.
Determination of “level of confidence” by MMC was based on the categorising the following seam characteristics as “simple”, “moderate” or “complex” based on the following criteria:
‰ variability of seam thickness including seam splitting, ‰ variability in coal quality parameters, and
‰ structural complexity.
The categorisation of resources at GBP Block 1 under this system is summarised in Table 4.5 below: Table 4.5—Resource Categorisation Parameters
Simple Moderate
Complex
Sedimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X
Coal Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X
Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X
Drill Spacing — Measured . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
500m 250m
100m — Indicated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
500-1,000m 250-500m
100-200m — Inferred . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1,000-1,500m 500-1,000m
200-400m Based on the level of complexity of the GBP Block 1 deposit, MMC sub-divided resources into
categories based on the following drill spacing: ‰ Measured
0-250m radius of influence 125 m. ‰ Indicated
250-500m radius of influence 250 m. ‰ Inferred
500-1,000m radius of influence 500 m. While the proposed open cut mine area has close drill spacing 50-200 m spacing, the lack of
geophysical logging and the use of “touch” coring for relatively thin seams has resulted in the resources being classified as of Indicated status in this area.
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The above level of confidence categories have been further modified seam-by-seam on the basis of the following factors:
Minimum No. of Drillholes For inclusion in the Coal Resource estimation a minimum of four overlapping drillholes are required for
the relevant category, in order to avoid “bulls-eyes”. Minimum Seam Thickness
Coal seams 0.4 m in thickness have been excluded from resource estimates due to the lower level of confidence in data for thin seams, due to the factors given below:
‰ some coal roof losses occur due to “touch” coring and this can be a material issue in the interpretation of thin seams, and
‰ limited coal quality data for thin seams. The drillhole density and the resource category polygons applied by MMC to one of the main seams is
shown as an example in Figure 5. Similar methodology was applied to other seams to determine resource limits. 4.6 Coal Resources
The parameters applied in the estimation of coal resources by MMC are as follows: ‰ no geological losses have been applied,
‰ minimum thickness of 0.4 m coal is reported, ‰ maximum thickness of parting included in seam thickness is 0.10 m,
‰ the Keham coal seams will likely be mined in relatively shallow multiple along strike pits where coal is of mineable thickness, therefore Coal Resources are reported above an elevation Reduced Level,
RL of plus 150 m, Note: elevation limitations have been applied in order to meet the criteria of JORC resource reporting of “reasonable prospects for eventual economic extraction”, and
‰ the Cilong Coal Resources are reported above an elevation RL of zero, and ‰ estimates for individual seams have been rounded to the nearest 50 kt for Indicated and 100 kt for
Inferred resources.
Total Geological Resources reported for both deposits are summarized on Tables 4.6 and 4.7. Table 4.6—Resources Summary—Keham Block
Seam Resources kt
Measured Indicated
Inferred Sub-Total
8U . . . . . . . . . . . . . . . . . . . . . . . . . . 1,200
100 1,300
8L . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
100 500
7U . . . . . . . . . . . . . . . . . . . . . . . . . . 300
200 500
7L . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,000
600 1,600
TOTAL . . . . . . . . . . . . . . . . . . . . . . 2.9 Mt
1.0 Mt 3.9 Mt
Note: Totals have reported in Mt and rounded up to one decimal place
Table 4.7—Resources Summary—Cilong Block
Seam Resources kt
Measured Indicated
Inferred Sub-Total
7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,400
2,400 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1,100 1,100
5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,200
800 2,000
TOTAL . . . . . . . . . . . . . . . . . . . . . . 4.7 Mt
0.8 Mt 5.5 Mt
Note: Totals have reported in Mt and rounded up to one decimal place A-24
