Mine Geology and Grade Control, June 2002

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Mine Geology and Grade Control, June 2002
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Grade Control at SDGM
Geology / Mineralisation Mineral Resources and
Reserves Grade Control Practices Reconciliations

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Local Stratigraphy
The Cleo/Sunrise orebody is hosted by a sequence
that is metamorphosed to greenschist facies and
comprises

• Intermediate volcanic and volcaniclastic rocks
• Conglomerates
• Banded Iron Formations
• Minor mafic and ultramafic intrusions
• Felsic porphyries
• Late lamprophyric dykes

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Mineralisation, Cleo Deposit

• Shallow Dipping Structures
• Sunrise Shear, Placer Upper Shear, Upper Shear
• Predominantly BIF hosted ductile structures, Low
  As
• Steep Dipping Structures
• Western Shear, Bells, Summercloud, Cosmo, Dolly
  others
• Volcanics / BIF hosted vein stockwork Brittle
  structures
• High Grade, High As, partially Refractory
• BIF hosted Mineralisation
• Upper BIF GQ
• Mixture of Shallow Steep styles
• Generally high grade

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Sunrise - Schematic cross section
CLEO
SUNRISE
UPPER BIFS
USZ
WSZ
PUSZ
Felsic porphyry
SSZ
Upper shear porphyry
Mafic (high Mg)intrusive unit
LP1
Ultramafic Intrusive Unit
Quartz diorite
LB3
BIF
Shear zones
CFZ
LB2
BIF -hosted mineralisation
Low - strain breccia/ stockwork mineralisation
LB1
High strain shear zone mineralisation
DSZ
Porphyry - hosted mineralisation
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Cleo mineralisation styles
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Resource Estimate

• Multiple Indicator Kriging, an estimate of
  recoverable resource
• Geological wireframes are prepared for the
  distinct geological domains
• Variograms of spatial continuity prepared for
  each geological domain
• Arsenic modelled as a secondary dependent
  variable
• Density modelling based on diamond drill core,
  inverse distance method.

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2001 Reconciliation

• 0.8 g/t COG Sap and Trans
• 1.2 g/t COG Fresh
• Includes Stockpiles

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Coarse Gold

• 50 of Mill recovery is from the gravity gold
  circuit
• Key issue in sampling, assaying estimation at
  SDGM

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Grade Control Methodology
Reverse Circulation Drilling Fire Assaying
Conditional Simulation Blast monitoring Qualified
Ore Spotters Site Wide Dilution Control
Training Continuous Mapping Closing the Loop
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• Grade Control Methodology

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Conditional Simulation

• Probabilistic
• Geological inputs

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Blast Monitoring
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Dilution Control Strategies

• Strategies have been developed to assist in the
  training of operators and field staff

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• Sunrise Dam Gold Mine
• Geologically Complex
• Structural Controls
• Lithological Controls
• Narrow Ore Zones
• Dilution Sensitive

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Innovation

• Cone Splitter
• Digital in-pit Mapping
• CSIRO Vision
• Conditional Simulation

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END