Pyramid Deposit


The Pyramid porphyry copper-molybdenum deposit is a quartz diorite porphyry and hornfelsed sediment hosted system, likely of calc-alkaline affinity. A maiden inferred resource has been established at Pyramid as the result of multi-phase diamond core drilling program. Antofagasta Minerals PLC drilled 30 core holes between 2010 and 2012 for a total of 7,458 meters. In addition to drilling, several geophysical surveys including ground magnetics and induced polarization (IP) were conducted simultaneously as was continued mapping and prospecting. June 2013 SRK Consulting authored an inferred mineral resource report that also contemplates additional drilling as the Pyramid deposit is still open laterally and at depth.

CopperBank Alaska Portfolio

Inferred Mineral Resource

At a 0.21% copper equivalent cut-off, total contained copper in the Inferred resource category is estimated to be 1,338,000,000 pounds of copper, 74,000,000 pounds of molybdenum and 488,000 ounces of gold. Both near-surface supergene enriched mineralization as well as hypogene copper mineralization were modeled and interpolated. The mineral resource estimate shows that the hypogene mineral resource remains open to depth and along strike in most areas, and the higher grade supergene enriched mineralization is also open for expansion in several areas.

Pyramid Inferred Resource Table May 1, 2013

Note: All numbers have been rounded to reflect the relative accuracy of the estimates.
Mineral resources are reported in relation to a conceptual pit shell. Mineral resources are not mineral reserves and do not have demonstrated economic viability. The contained copper represents estimated contained metal in the ground and has not been adjusted for metallurgical recoveries.

Supergene Resources
Under zero to 90 meters of leach cap, the Pyramid deposit hosts a supergene enrichment blanket, dominated by chalcocite and local covellite mineralization. The supergene blanket has a variable depth, extending to below 250 meters surface in some areas.
At a 0.21% copper equivalent cutoff, this near surface supergene enrichment zone hosts 93.7 million tonnes averaging 0.40% copper, 0.019% molybdenum and 0.092 g/t gold, or 0.55% copper equivalent. This equates to 823,000,000 lb. copper, 40,000,000 lb. molybdenum and 277,000 oz gold. Several areas have been identified to date with near-surface high-grade mineralization within the supergene zone, particularly in the south-central area of the inferred resource. These areas include drill hole PY11-016, which, intersected 155.90 meters averaging 0.71% copper, 0.179 g/t gold and 0.018% molybdenum or 0.91% copper equivalent. 250 meters southwest of PY11-016, drill hole PY12-019 encountered a high-grade zone of supergene enrichment averaging 1.01% copper, 0.165 g/t gold and 0.009% molybdenum or 1.16% copper equivalent over 42.0 meters, occurring near surface at 24.0 meters down-hole.
Hypogene Resources
Underlying the supergene zone in most areas, the hypogene zone hosts 79.1 million tonnes averaging 0.26% copper, 0.020% molybdenum 0.083 g/t gold, or 0.45% copper equivalent at a 0.21% copper equivalent cutoff. This equates to 514,000,000 lb. copper, 35,000,000 lb. molybdenum and 212,000 oz gold. The hypogene zone is open for expansion to depth in most areas, as most holes completed to-date at Pyramid are 250 meters long or less. Only two drill holes have been completed to depth of 500 meters.


The primary objective of the 2012 drill season was to test extensions of copper-gold-molybdenum mineralization, as well as follow up on high grades encountered during the 2011 drilling program. Portions of the surface expression of stockwork veining and favorable alteration have not yet been drilled at Pyramid, and mineralization is open in several directions and at depth.
The 2012 program is the third drilling season funded by Antofagasta Minerals S.A.. Drill holes were typically shallow for a porphyry system, with most holes less than 300 meters in total length. Drilling during 2010 and 2011 spanned an area measuring approximately 1,100 meterseast-west and 900 meters north-south. 2012 drilling tested beyond these limits, and in particular, tested for areas of near-surface supergene copper enrichment.
Several hydrothermal centers have been identified at Pyramid, within an oval-shaped 2,300 meters by 1,400 meters mapped extent of phyllic and potassic alteration zones. Classic vein styles are identified in drill core and surface expressions, with early halo veins, A, B, and D veins hosting mineralization. Copper mineralization with variable molybdenum occurs within multiple phases of porphyritic intrusive rocks as well as hornfelsed sedimentary country rocks. Quartz diorite porphyry and quartz feldspar porphyry intrusions make up the bulk of the igneous rock types and hosts.
Mineralization is typically comprised of chalcocite, covellite, chalcopyrite and molybdenite with supergene enrichment at depths ranging from 120 to over 250 meters below surface.

During the 2011 season, twelve holes were completed totaling 2,576 meters. The drill holes, with most less than 300 meters in length, shallow for a Porphyry system, were designed to test for grade. Drilling spanned an area measuring approximately 1,100 meters east-west and 900 meters north-south, is open for expansion in all areas and at depth.
Of significance was drill hole PY11-016 which intersected 155.94 meters averaging 0.71% Cu, 0.179 g/t Au and 0.018% Mo, or 0.97% Cu equivalent underneath a 94.0 meter thick leach cap. The intercept includes several higher grade zones, including 20.0 meters averaging 0.99% Cu, 0.151 g/t Au and 0.012% Mo, or 1.19% Cu equivalent. This hole was shut down in strong mineralization, with the final 7.94 meters averaging 0.78% Cu, 0.124 g/t Au and 0.03% Mo. This hole was completed at the extreme of southeastern area of drilling to-date, suggesting a grade and hydrothermal vector in this direction.
Drill hole PY11-017 was a 60 meter northeast step-out from hole PY10-05, which encountered 72.0 meters averaging 0.75% Cu, 0.162 g/t Au and 0.017% Mo (0.957% Cu. Equiv). This hole intersected 117.54 meters averaging 0.60% Cu, 0.081 g/t Au and 0.024% Mo, or 0.81% Cu equiv. Mineralization remains open to expansion to the north.

pyramid-drill-locations-2010-2011-2012Pyramid Block Model using a 0.20% Copper Only cut-off (no credits included) demonstrating continuity and drilling potential.  View full drill result table in PDF presentation.


Hole PY11-16 bottoms in 34m of 0.84% Copper. Note the 2012 drill program (red holes in drill map photograph) did not follow up in this area.

DD PY11-16


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