Diente Verde Project
The Diente Verde Project consists of a combination of deposits covering a total area of approximately 7,100 hectares in the San Luis Province, west central Argentina. The project is located in one of Argentina’s prime economic regions referred to as Cuyo. This region includes the provinces of San Luis, Mendoza and San Juan, all of which have strong economic ties to Santiago, Chile. The Cuyo region has well developed infrastructure in terms of transportation, communications, electrical power and water supply that are all capable of supporting a strong and expanding industrial and agricultural base. Access to the project is a few hours’ drive from the city of San Luis via paved roads. The climate is temperate and the project can be worked year round. Water and electric power are also readily available in the area, as well as the ancillary services and skilled labor required to support a mining operation.
Geology and Mineralization
The Diente Verde Project lies in the Sierras de San Luis, part of the early-mid Paleozoic metamorphic terrain known as the Pampean Sierras, which consists of Cambrian to Devonian age deformed metamorphic intrusive rocks. Tertiary age volcanic centers occur in a northwest-southeast belt approximately 90 kilometres in length, which intrude the basement metamorphic rocks. These volcanic rocks consist of flows, domes, dykes, tuffs, intrusive and breccias that are calc-alkaline to shoshonitic. The hydrothermal alteration and mineralization events are of Miocene age and are believed to have occurred during the later stages of volcanic-intrusive activity. The alteration and mineralization stage was followed by a volcanic event, which capped the alteration and mineralization zones in the region.
Mineralization at the DV Project consists of pyrite and secondary magnetite in quartz veins, resulting from hydrothermal alteration. The high levels of gold and copper found on the project through previous production are related to quartz-magnetite stockworks filled with chalcopyrite and bornite, with extended potassic alteration.
Four main hydrothermal alteration systems (the Diente Verde, Cerro Redondo, Cerro Pelado and Cerros Largos targets) have been identified, all related to flat-slab, late Tertiary age volcanic activity. The Diente Verde alteration zone covers approximately two square kilometres within an eight square kilometre volcanic intrusive complex and alteration consists of a broad argillic (phyllic) zone which replaces volcanic breccias and andesite-dacite flows. Contained within the argillic zone are two zones of potassic alteration (DV and Mario Showings) which are associated with intrusive monzonite-porphyries. The altered rocks are overlain by unaltered andesite flows.
The DV and Mario Showings are found within the Diente Verde alteration zone and are considered to be the current primary production targets on the DV Project. The DV Showing occurs as a prominent topographic feature (volcanic cone) some 600 metres in diameter and 400 metres in height. The Mario Showing, located one kilometre to the east of the DV Showing, is exposed as a low topographic feature expressed as an altered gossan. The DV and Mario Showings consist of intrusive-porphyry centres of stockwork veins and disseminations containing gold-copper-silver mineralization associated with the potassic alteration. The alteration assemblage of the intrusive centres (potassic zone) consists of quartz, fine-grained biotite, albite and K-feldspar, and the ore assemblage consists of chalcopyrite, pyrite, electrum, free gold, digenite, tennantite, bornite, covellite, pyrrhotite, magnetite, ilmenite, rutile and specularite. Significant gold, copper and silver mineralization, on surface and at depth, has been found on the DV and Mario Showings as follows: 0.10 to 7.55 grams of gold per ton; 0.20% to 1.17% copper; and, 1.0 to 13.8 grams of silver per ton.
Mineralization was initially discovered at Diente Verde in the early 1960s by a prospector who identified malachite containing outcrops in the area, which resulted in the staking of Diente Verde prospect. A subsequent three hole diamond drilling program conducted by Minera Aquilar returned elevated copper values, however no analysis for gold was conducted. During the 1970s, the Diente Verde area was sporadically explored for copper and prospected by geologists of the Dirección General de Fabricaciones Militares, a country-related military enterprise.
In 1996, Goldcliff Resource Corporation (“Goldcliff”) acquired the production and mining rights for the DV Project, investing approximately US$2.5 million on production and development of this area through to 1999 when it was relinquished due to a change in the company’s production focus. At the time, the entire Diente Verde Project covered approximately 6,500 hectares and consisted of three fully surveyed and registered mining claims (300 hectares) and four cateos (6,200 hectares). Goldcliff’s production efforts were focused on the Diente Verde Prospect, a two square kilometre sized alteration zone contained in Tertiary volcanic and intrusive rocks, which hosts the DV, Spring and Mario Showings. The DV Showing comprises a core zone of potassic-silica-magnetite alteration containing disseminated and stockwork sulphides, as well as oxides with significant gold and copper values. The core zone is poorly exposed within a caldera setting and is just beginning to weather-out from the capping volcanic flows.