Avocet Mining PLC Prospectus December 2011

Avocet Mining PLC
West African Projects
Five block models were constructed, one for each mineralized deposit. The size of parent blocks
were based on half the typical drill spacing, with sub‐blocks used to ensure the block model honored
the mineralized zone geometries. For the north – south striking deposits (Inata North, Central, South
and Sayouba) the models were constructed using a parent cell size of 10m x 25m x 5m (X x Y x Z)
with sub‐cells down to 2.0m x 5m x 1.0m to model the steeply dipping narrow lenses. Minfo East
used a parent cell size of 25m x 10m x 5m (X x Y x Z), reflecting the east‐west strike of this
mineralisation.
Search neighbourhood parameters were evaluated for each deposit, with varying search radii. The
maximum number of samples used was 48, and an octant based search was applied. Cells were
discretized to 2 x 5 x 5.
Block grades were estimated using ordinary kriging (OK) and inverse distance weighting squared
(IDS) interpolation methods. The results of the grade estimation were validated by means of visual
comparison along sections, statistical analysis, and trend plots comparing the estimated block grades
and the drill hole sampling grades. The IDS estimation was also found to correlate well to the OK
estimation method.
The Mineral Resource estimates were classified according to JORC reporting guidelines. Geological
and grade continuity were assessed per deposit. Inata North and Inata Central are currently being
mined, and geological observations via mapping and mining reconciliation influenced the final
classification for these deposits. QA/QC data from drill samples and density data were reviewed and
were also considered during final classification. The classification boundaries from the 2010 Mineral
Resource models were loaded as a starting point, with the aim being to either retain the boundary
locations, or shift Indicated regions into Inferred, and Measured into Indicated. Perimeter strings
were digitised along a nominated easting or northing (Minfo East) outlining Measured, Indicated and
Inferred regions. The base of Indicated is nominally between 25m and 50m below the deepest drill
intercepts.
The Mineral Resource has been reported above a lower cut‐off of 0.5g/t gold (Table 18), and has
been depleted by topography, which represents the mining open pit surface as of 30 th June 2011.
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