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
interpreted to be the result of sinistral movement along the two north-south oriented
bounding faults mentioned earlier (Figure 7.4).
7.4 Alteration
Wallrock alteration is spatially associated with the main vein system trends at Pulacayo and
includes propylitic, sericitic, moderate-advanced argillic, and siliceous assemblages. Host
rock composition exerts a strong local influence on both the nature of alteration
assemblages present and their relative intensity of development. On this basis, spatial
distribution of hydrothermal alteration assemblages in the district is a useful indicator of
proximity to mineralized structures. Moderate argillic alteration is observed throughout the
Pulacayo area and transitions to intense argillic alteration in close proximity to veins and
disseminated-stock work zones. Haloes of silicification are developed around vein contacts
and measure up to several cm in width in some cases. Silicification grades into advanced
argillic alteration as distance into the wall rock increases from the vein contact and this
gradually grades to argillic and propylitic zones with greater distance from the contact.
7.5 Mineralization
As referenced by Pressacco et al. (2010) the Pulacayo deposit is considered an example of
a sub-volcanic epithermal mineralization system showing well developed vertical metal
zonation. The main mineralized vein and stock work system developed on the southern flank
of a dacitic intrusive dome and shows a surface strike dimension of 2 700 m. At Pulacayo,
east-west striking faults are interpreted to have acted as a conduit system for mineralizing
fluids, with sulphide precipitation in open spaces to form veins and along fractures or by
replacement to form zones of disseminated mineralization. Changes in temperature,
pressure and redox state between the wall rock and fluid are thought to have influenced the
style and intensity of mineralization. As such, Ag-Pb-Zn lead mineralization at Pulacayo is
typical of a high level epithermal system that in this case is hosted by sedimentary and
intrusive rocks of Silurian and Neocene age.
The principal mineralized structure at Pulacayo is the TVS, which has historically been the
main Ag producer of the mine. The TVS is a large structural stock work system that trends
east-west and dips 75° to 90° to the south (Figure 7.4). The high grade parts of TVS were
historically mined as single veins over widths of 1 m to 3 m but transitions from this setting
into zones of complex quartz-sulphide or sulphide vein arrays that include conjugate veins,
veinlets, stock works and disseminated sulphides that occur over widths ranging from less
than a meter up to 120 m.
Mineralization of economic interest at Pulacayo is predominantly comprised of sphalerite,
galena and tetrahedrite in sulphide-rich veins that are accompanied by locally abundant
quartz, barite and pyrite. These veins range from a few centimeters to greater than 1 m in
thickness and disseminated sphalerite, galena and tetrahedrite typically occur in wallrock
between the veins. Disseminated mineralization is preferentially developed around and
between veins hosted by andesite. To date, the TVS system has been continuously proven
by mining and/or surface exposure along a strike length of 2,700 m and to a vertical depth of
1,000 m below surface and was open in both strike and dip components at the effective date
of this report. The first 450 vertical meters of the TVS is hosted by andesitic volcanic rocks
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