The calculation parameters for the reserves are:
Ore density: 2.75 t/m³.
Grade of drilling samples: 68.5 g/t.
PARAMETERS FOR ROOM-AND-PILLAR STOPE
- Stope of 6 m to 10 m (20 ft to 33 ft) wide in the vein plan
- Square pillar of 3 m (10 ft) or longitudinal of 2 m (6.6 ft) in the vein plan
- Maximum dip: 40 degrees
ORE RECOVERY: 90% (10% from pillar).
- Internal: Minimal mining thickness: 2 m (6.6 ft) with 10 degree dip, and 2.5 m (8.2 ft) with 35-degree dip. (The drilling intersections are brought to a minimal thickness of 2 m or 2.5 m.)
- External: 5% of the waste will be mined with the ore and therefore included with the reserves.
CUT-OFF GRADE (economic limit):
- Room-and-pillar stope developed: 7.39 g/t
- Room-and-pillar stope non-developed: 7.93 g/t
- Longhole stope developed: 5.13 g/t
- Longhole stope non-developed: 5.67 g/t
PARAMETERS FOR LONGHOLE STOPE
- Stope of a maximum length of 30 m (98 ft).
- Minimum dip: 45 degrees.
- 85% for the sections of the stopes that were not planned.
- 100% for the planned stopes; the pillars are excluded from the reserve.
- Internal: Minimum mining thickness: 3 m (10 ft). (The drilling intersections are brought to a minimal thickness of 3 m.)
- 10% of the waste will be mined with the ore for the primary stopes (Zone B).
- 15% of the waste will be mined with the ore, and therefore included in the reserve.
CUT-OFF GRADE (economic limit):
- Developed stope: 5.38 g/t.
- Undeveloped stope: 5.83 g/t.
CALCULATION PARAMETERS OF RESERVES
- Minimum thickness: usually 3 m (10 ft).
- Economic grade: 4.5 g/t of gold, based on the following econimical parameters: Gold price of US$300 per ounce at an exchange rate of 1.5 $CAN/US.
- Cut-off grade from individual drilling analysis: 70 g/t. On the average, the grade varies depending on the zone.
- Ore density: average of 3.8 t per cubic meter. Waste density: 2.8 t per cubic meter.
- Dilution: Dilution is included in calculations. In 2001, it was estimated at an average of 20% ; in 2002, at 30%.
- Recovery rate after mining: 95%.
RESERVE CALCULATION PARAMETERS
- Minimum thickness: - generally 1.6 m (5.25 pi) for Lenses 50 and 60 - 1.9 m (6.2 pi) for Lens 40 - 1.6 m (5.25 pi) for Lens 08
- Economical grade: 9.6 g/t gold. Calculated according to the economical parameters: - Gold price: US$325/oz - Exchange rate: 1.45 (US$ to CAN$) - Production cost: CAN$136.9/t
- Cut-off grade for drilling analysis: - Zones 40 and 50: 150 g/t in the Proven and Probable 1 categories - Zone 8: 34 g/t for all of the analysis.
- Ore density: 2.8 tonnes/m³.
- Dilution: The reserve calculation includes the dilution. It is estimated at 5% for Zones 08, 50 and 60, and at 12% for Zone 40.
RESERVE CALCULATION PARAMETERS
- Minimum width: generally 3 m (10 ft).
- Cut-off grade: 4.1 g/t of gold, calculated according to the following economic factors: Gold price of $300 US/oz and exchange rate of 1.50 in Canadian dollar.
- Ore density: 2.85 t per cubic metre.
- Dilution: estimated at 20% and is included in the calculation.
- Recovery ratio after mining: 95%.
- Price of gold: $300 U.S.
- Exchange rate: 1.5
- Cutoff grade: varies from 60 g to 250 g (2 to 8 oz), depending on the lens and the stopes, based on the sampling statistics.
- Minimum thickness: 1.4 m or 1.8 m (4.6 ft or 6 ft) true width along the dip of the evaluated lens.
- Density of the ore: 2.9 t/m.
- Shrinkage stope: 15% with no grade except for zone 30 with a dilution of 10% with no grade.
- Long holes : 30% with no grade. The reserves are based on the long term economic limit. The marginal economic grade prevails for the active or entirely developed stopes and must be used in production surplus.
- Maximum grade: 68 oz/t.
- Minimum width for mining reserve: 1.8 m (6 ft).
- Ore recovery at the mine: 86% (14% of reserves are left in pillars).
- Ore recovery at the mill: 94.03% in 1998; 94.28% in 1999. The grade of milled ore is higher than planned.
Every year the reserves are audited by an external consulting firm (ACA Howe International Ltd.). The mine reserves are quarterly calculated.
- Minimum width: 1.2 m (4 ft).
- Cut-off grade: 6 g.
- Recovery factor: 85-90%.
- Mineral density: 2.67.
- Grade applied to dilution: 1 g/t.
- Dilution factor: 12.5%. The dilution is applied only on the reserves, not on the broken reserves.
- Price: Cu equivalent (Ni, Cu, Au, Pt, Pd, Ag).
- Minimum mining width: 2.1 m (7 ft).
- Specific Gravity (SG): 3.2.
PARAMETERS AS OF JANUARY 1999:
- Price of gold used: US$350/oz with an exchange rate of 1.455; C$509/oz = C$16/g
- Operation costs: see attached document.
- Ore recovery at the mill: 97.0%.
- Cut-off grade:
- 5.76 g/t in room and pillar stopes, shaft 2.
- 5.9 g/t in room and pillar stopes, Lamaque.
- 5.8 g/t in conventional cut and fill.
- 5.46 g/t in mechanized cut and fill.
- 5.0 g/t in Vbr cut and fill.
- 3.95 g/t in Sigma long holes.
- 4.04 g/t in Lamaque long holes.
- 4.53 g/t in shrinkage stope.
- Density: 2.67 t/ m³.
- Dilution factor: Each reserve block is examined by the geology and engineering departments to determine which mining method and dilution factor is appropriate.
The factors are generally the following:
- - room and pillar: 1 vein = 1.8 m of mining height.
- - shrinkage stope: 15%.
- - cut and fill: 20%.
- - long hole 1.8 m (6 ft) of power: 33%.
- - long hole 2.4 m (8 ft) of power: 25%.
- - long hole 3.0 m (10 ft) of power: 20%.
The width of the zones (1.8 m, 2.4 m and 3.0 m) is defined in function of the structures as well as the linearity.
HIGH CUT-OFF GRADE AS OF JANUARY 1, 1999:
- Chip sample: 34.29 g/t at Sigma and 85.00 g/t at Lamaque.
- Muck sample: 25.00 g/t at Sigma and 25.00 g/t at Lamaque.
- Drill core: 34.29 g/t at Sigma and 85.00 g/t at Lamaque.
TONNAGE AND GRADE CALCULATIONS
The 3D model defines the orebody. This model, in turn, is divided into 3 m x 3 m x 3 m (10 ft x 10 ft x 10 ft) blocks. The grade and tonnage of these blocks are based on the following parameters:
- Diamond drill assays are cut to 56 g/ton (2.0 oz/ton).
- Grade calculations for the individual ore blocks are derived by an inverse distance cubed relationship with a search radius of 22.8 m (75 ft).
- Tonnage factor of 0.31 cubic meter/ton (11.2 cubic foot/ton).
- Gold content of the individual blocks is the product of: (derived tonnage) x (length weighted grade)
- The individual ore blocks are initially assigned a dilution factor of 20% and a dilution grade of 1.4 g/ton (0.05 oz/ton). Once a mining method has been selected for an individual mining block (stope), the dilution factor may be changed as follows:
The minimum mining width is 1.8 m (6 ft) for conventional mining and 2.4 m to 3 m (8 ft to 10 ft) for mechanized mining.
- Cut-and-fill: 15%
- Mechanized Cut-and-fill: 20%
- Shrinkage: 20%
- Longhole: 25%
- Blind Longhole: 30%
ORE RESERVE PARAMETERS:
- Price of gold: $300 US.
- Variable dilution ranging from 10% to 25% based on ore width.
- Dilution is applied at 0 grade.
- Erratic high assays are cut to 102.86 g/t (3oz/t).
- Wall rock cut off: 2.8 g/t approximately.
- Maximum stope recovery of 95%.
The minimum cut-off grade is established at 2.8 g Au/t (0.10 oz Au/t), while any sample with a grade higher than 28 g Au/t (1.0 oz Au/t) is troncated to 28 g Au/t (1.0 oz Au/t).
The tonnage factor used is 0.33 cubic metre per tonne (11.5 cu.ft/t). This factor was measured at the East Malartic mill.
The true minimum thickness of 1.7 m (5.5 ft) is applied. The narrowest intersections are diluted up to 1.7 m (5.5 ft).
A dilution of 15% at a grade of 0.57 g Au/t (0.02 oz Au/t) is added to the proven and probable tonnes.
CALCULATING PARAMETERS FOR RESERVE EVALUATION
- Cut off grade for drill hole: #6 Zone: 140 g (4.5 oz). #8 Zone: 60 g (1.9 oz). #2 Zone: 80 g (2.57 oz). #7 Zone: not enough data yet but 80 g to 100 g (2.57 oz to 3.2 oz) used.
- Minimum of 1.4 m (4.5 ft) of true width.
- Mineral density of 2.7.
- Grade given to dilution: 0.5 g/t (0.016 oz/t)
- Dilution: 20% for shrinkage stope and 30% for longhole stope. The recovery is presently 100% since no pillar is considered. This situation might change as ground conditions change.
Probable Reserve Parameters:
- The cut-off grade: 0.160 oz/ton when diluted at 30%.
- The specific gravity: when available, a measured specific gravity is used for each ore intersection. Otherwise, an average specific gravity of 2.8 is used.
- External Polygon maximum size: 30 m (98 ft) radius or halfway to the nearest waste hole.
- Internal Polygon maximum size: 80 m (262 ft) radius or halfway to the nearest ore hole.
- Minimum Mining Width: 2.44 m (8 feet).
- Cross-sectional analysis: 2.0 oz/t.
- Cut-off grade analysis: 0.080 oz/t.
- Mining dilution:
Adjustment Factor for Dip:
- Ore width less than 4 m: 30%.
- Ore width from 4 to 6 m: 20%.
- Ore width over 6 m: 10%.
- Dilution degree: 0.016 oz/t.
- For all Zones Level 1 to 4: 1.3054 (50 degrees).
- Level 4 to 6: 1.2208 (55 degrees).
- Level 6 to 10: 1.1547 (60 degrees).
- Surface drill holes, where required.
- Underground drill holes.
- Composited chip sample data.
Proven reserve parameters:
Proven reserves were calculated using a strict 30 m (98 ft) radius polygon, within the zones of continuous ore. All other parameters were the same as those used to calculate probable reserves.
The following parameters were used to estimate the resources at the New Britannia Mine:
- The diluted block cut-off grade for Ore Reserves is 0.080 oz/t Au. This replaces the diluted block cut-off grade for the Ore Reserves of 0.094 oz/t Au used in last year's document. This change is a direct result of the semi-annual review of the cut-off grades. This review is conducted in light of the changing gold price, mining costs, etc, and includes models for both short range (2000) and long range planning purposes.
- Due to the extremely limited number of high grade assays at the New Britannia Mine, assays above 1.000 opt were cut to 1.000 opt. A review of the validity of this cutting factor was conducted in 1988.
- Stoping widths are calculated to a minimum true width of 2.1 m (7 ft) for the geologic in-situ reserve. Current mining methods do not permit the ore zones any narrower than this without significantly changing the economics.
- The ore reserve and resource blocks are designed from sill level, based on the mining plan at the time reserves are being calculated. Since 1997, the blocks (excluding the Toots Zone) have been based on a sill spacing of 15 m (50 ft) vertical, to account for the periodic flattening of the orebody. For the 1999 reserves, this spacing has been continued for the Dick and Hogg Zone. The sill spacing for the Ruttan Zone has been changed to 40 vertical feet, due to the extreme flattening of the orebody encountered during mining below the 2606 Level.
- In the few cases where the assay data is missing (typically in historic drill data), they were assigned a weighted average value comprised of the closest two or more values on either side. Use of the weighted average began with the 1998 document. In prior documents, the missing data were assigned a value of 0.00 opt.
- A tonnage factor of 0.32 cubic metre (11.2 cubic feet) per ton was utilized. This value was calculated by INCO Gold during their 1989 exploration program. This factor has been confirmed both by an internal review as well as external review by Lakefield Research.
- An estimated mine recoverability of 90% was used. This is the balance between the material left behind in addition to ore material gained and mined within blocks. This recoverability was first used in the 1998 Document. The documents previously used an estimated recoverability of 95%. This change resulted directly from the way in which the reserves are calculated.
- The diluted reserves consist of the in-situ reserves plus the addition of 60 cm (2 ft) of material along the footwall and 90 cm (3 ft) along the hanging wall of each zone, with a calculated grade for each block. The footwall and hanging wall dilution is added after the in-situ reserves are taken to the 2.1 m (7 ft) minimum true width. In 1998, a study was conducted in order to determine the footwall and hanging wall dilution as compared to the previous method of determining dilution.