Pulacayo Project Feasibility Study - Apogee Silver

Pulacayo 1 000 t/d Phase I Feasibility Study - NI 43-101 Technical Report
090644-3-0000-20-IFI-100
Figure 14.2: Isometric View of the Oxide-Sulphide Transition Surface DTM – View to NW
Sectional interpretation showed that although silver and lead grade continues across the
oxide-sulphide boundary, the metals show depletion in the oxide zone. Zinc assay core
results are low to anomalous within the oxide zone and are interpreted to be almost
completely depleted. On this basis, the oxide-sulphide surface DTM model was used as a
hard boundary in grade interpolation, with assay composites unable to contribute to the
interpolation of blocks on opposite sides of the surface.
14.3.4.3 Domain Modeling
The spatial distribution of volcanic host rocks and sulphide-silver mineralization contributes
directly to variability in grade distribution within the Pulacayo deposit as defined by Apogee
drilling. Stringer and disseminated style mineralization with locally massive to semi-massive
zones are typical of the TVS within the intruding andesitic volcanics. Despite observed
deposit scale zonation of all three metals throughout the history of mining, with higher grade
silver occurring at middle elevations and increasing base metal values with depth, the TVS
can locally be defined by any one metal or various combinations of the three.
The previous resource estimate by Mercator used an NSR-based spatial domain model to
define that portion of the TVS having the greatest economic potential. Although this method
accommodates spatial grade variability within the deposit and adequately constrains
interpolation, a smearing effect of each metal can potentially occur by diluting higher-grade
vein based mineralization into lower-grade adjacent tons from the lack of hard individual
grade boundaries for high grade structures. Detailed sectional geological modeling
subsequent to the previous resource allowed development of a more precise correlation of
veining and associated mineralization, resulting in a transition from the NSR-domain
methodology to the individual metal domain methodology used in the current resource.
Assay results for silver, lead and zinc were displayed on drill hole traces at nominal 50 m
section spacing and sectional interpretations for each metal based on these values were
used to develop metal-specific, independent, three dimensional wireframe solid models. The
TWP Sudamérica S.A. Av. Encalada 1257 Of. 801, Santiago de Surco Lima 33, Perú (51-1) 4377473
Page 118