The Arikepay Copper-Gold Porphyry Discovery

Location Map

Arikepay is 100% owned by Alta Copper and consists of 3 claim blocks totaling 1,800 ha.  The property is located about 110 km south of the city of Arequipa in southern Perú and 45 km south of the +3 billion tonne Cerro Verde Cu-Mo porphyry deposit, owned by Freeport, SMM Cerro Verde Netherlands and Buenaventura.

In 2010, Company geologists carried out a program of mapping and rock sampling from shallow hand-dug pits in an area of poorly exposed and strongly limonitic intrusive and volcanic rocks.  Mapping and strongly anomalous copper, gold and silver results from this work indicated potential for porphyry style mineralization.  In addition, the potential for mineralization to extend to the northwest under younger alluvial cover was recognized. 

In May, 2012 a 775 line kilometre high resolution helicopter-borne magnetic survey was completed and in June 2012 a reverse circulation (RC) drill program of 14 holes for 3,630m was completed.  Drilling results confirmed the presence of a north-northwest trending zone of propylitic, phyllic, silicic and potassic alteration of varying intensity that extends for approximately 2,200m and over a width of approximately 700m to 1,200m and to a depth of at least 300m (machine limit). Over half of this zone occurs under alluvial cover. Within the larger area of alteration and mineralization lies an area of significant copper-gold-silver mineralization that measures approximately 1,200m by 800m. Mineralization consists of disseminated and fracture filling pyrite and chalcopyrite, and varies from copper-dominant to gold-dominant to silver-dominant.

Selected highlights from the RC drilling program include:

  • 142m of 0.51% CuEq* in hole RC-12-ARI-006
  • 186m of 0.43% CuEq* in hole RC-12-Ari-011
  • 292m of 0.39% CuEq* in hole RC-12-Ari-002
  • 146m of 0.31% CuEq* in hole RC-12-Ari-003
  • 170m of 0.31% CuEq* in hole RC-12-Ari-013
  • 80m of 0.35% CuEq* in hole RC-12-Ari-005

*Copper equivalent (Cu Eq) grades include gold and silver values based on 100% metal recoveries and the following metal price assumptions: US$1,200 per troy ounce gold, US$20 per troy ounce silver, and US$2.50 per pound copper.

In December, 2013 Compañía Minera Zahena S.A.C. (Zahena) optioned the property and completed a diamond drilling program of 14 drill holes for 8,907.80m in March 2017.  This program was designed to investigate the mineralized system at depth.  Drill holes range from 500m to 706m in depth.  Drilling encountered propylitic, phyllic, silicic and potassic altered volcanic and intrusive rocks.  Mineralization consists dominantly of pyrite ranging from <1% to >10% in disseminations and veinlets with lesser amounts of chalcopyrite, bornite and magnetite.  Zahena subsequently discontinued the option due to low copper grades. 

Highlights from the diamond drilling program include:

  • 357.00m of 0.29% Cu, 0.11 g/t Au, 1.16 g/t Ag, 0.007% Mo in hole AK-DDH-10-17
  • 420.00m of 0.04% Cu. 0.905 g/t Au, 1.16 g/t Ag in hole AK-DDH-02-17
    • Including 81.00m of 3.052 Au, 2.041 g/t Ag
    • Including 18.00 of 1.087 g/t Au, 0.1 g/t Ag

The significant gold and silver mineralization intersected in drill hole AK-DDH-02-17 (81m of 3.052 g/t Au and 2.041 g/t Ag) is associated with strongly silicified and pyritized intrusive rocks near the volcanic –  intrusive rock contact.  Higher gold grades were also encountered in the nearby RC drill hole RC12-Ari-02 which intersected 26m of 1.290 g/t Au and 4.5 g/t Ag.  There is potential for this gold zone to continue for at least 1 km to the northwest along the southwest flank of the larger system. 

To date there has been no follow-up to this gold potential and the Company is various options to further explore the gold potential at Arikepay.