Crosby and Pirquitas Norte are located in NW Argentina in the Province of Jujuy within the Departments of La Rinconada and Cochinoca.
They are in close proximity to the Silver Standard Pirquitas Mine, a large, medium grade silver-tin-zinc deposit with reported reserves of just under 200 million ounces of silver and Glencore's Aguilar, a large skarn replacement deposit with historical production exceeding 25 million tonnes of ore mined at an average grade of 6.2% zinc, 5.5% lead and 60-100 g/t silver.
Pirquitas NW prospect:
A large, 1.7 km by 1.0 km target zone with coincident geochemical, geological, structural and geophysical anomalies suggesting it could be a satellite system along strike from the Pirquitas mine mineralization.
Noelia Breccia Prospect:
A potential Au-Ag epithermal system on the Noelia Breccia prospect consists of a large mapped outcrop 1.6km by 0.8km on the eastern limb of the anticline structure which hosts the Pirquitas Mine. Anomalous values up to 120ppm As, 137ppm Sb, 249ppm Zn, 23ppb Au and 256ppm Cu.
A good geochemical correlation was observed between Au-Ag, As-Sb-Hg and Cu-Cd-Zn, which is considered as an affinity with epithermal systems containing Au-Ag mineralization.
While no intrusive structures are seen at surface it is evident that the Ordovician sediments are domed upwards around the old mine with upper formations highly altered and argillized and deeper formations comprising more indurated and partly silicified rocks closer to the mineralized zone. These formations plunge at shallow angles to the east, west, north and south and below the Crosby & Pirquitas Norte properties and are considered highly prospective at depths greater than those already proved up within the Pirquitas Mine.
These properties surround the Pirquitas Mine where a stockwork system carries Ag-Sn-Zn of economic tenor and has recently been redeveloped into a producing mine. This stockwork system is developed around an anticlinal form which plunges northward, westwards, southwards and eastwards beneath the Crosby & Pirquitas Norte properties. Evidence of potential mineralization is seen at surface in a halo of alteration surrounding the Pirquitas mine, some of which passes on to these properties. If a continuation of mineralization is to be found it is inferred from this anticlinal form that this will be found mainly in depth.
The Noelia Breccia Prospect straddles the Crosby and Pirquitas Norte properties which surround the Pirquitas Mine properties on three sides. The prospect was initially identified as part of reconnaissance work completed by Artha, the first systematic modern exploration ever done in the area and lies 2km to the N-NE of the Pirquitas mine itself.
Mineralogically, the the Noelia Breccia Prospect corresponds to a low sulphidation epithermal system with obvious quartz veinlets and breccia textures in outcrop coupled with intense silicification also observed. The breccias is controlled by faults and fractures within E-W and NW-SE cross-cutting structural system with the key feature being approximately 1.2 x 0.8km in size. The silicified structures consist of sets of unidirectional veinlets with dimensions between 100 to 500 m in length and 1 to 5m in width. The scale of this breccia and its associated alteration halo is considered indicative of a broad and potentially large mineralized system, with the large circular IP chargeability anomaly coincident with this surface expression thus greatly enhancing the prospectivity.
The latest work program consisted of detailed mapping and surface sampling at a scale of 1:10,000, over an area 700 hectares. Surface geochemical sampling was completed on a 100 x100m grid with systematic sampling of structures. A total of 212 surface samples were collected, of which 20 were duplicates to control QA / QC. Samples were sent to ALS-Chemex laboratory in Mendoza Province for preparation and to Lima, Peru for analysis. Four hand samples were selected for petrographical analysis.
The geochemistry from the recent work provides two large and strong anomalies with multiple correlated pathfinder metals, consistent with the signature of a low sulphidation epithermal system. The anomalies are delineated by elevated arsenic-antimony-mercury-lead-zinc and copper values over broad areas. Gold is also elevated in a small number of samples. The dimensions of the highest priority anomalies are approximately 450 x 180m and 200 x 100m respectively.
The Pirquitas NW prospect lies to the NW of the Pirquitas mine and consists of a 1.7 km x 1.0 km target zone hosted in Ordovician sedimentary rocks (shales and sandstones) where a range of mineralization indicators have been identified including breccias, veins and stockwork systems oriented E-W and NNE-SSW, consistent with the mineralized trend of the region. The target zone is partly covered by quaternary soil however a quartz-sericite core with iron oxides (OxFe) and metal sulfide mineralization surrounded by an argillic halo exists. The main observed mineralization is hematite and limonite in fractures with quartz veins and breccia matrix. Sulphides such as pyrite, chalcopyrite, arsenopyrite, galena, sphalerite have been observed associated with stockwork quartz veins and some historical exploration and workings.
Rock chip sampling recently completed has reported high priority anomalies with coincident gold (up to 2100 ppb), silver (up to 23ppm), arsenic (over 10,000 ppm), antimony (up to 433ppm), zinc (up to 17,350 ppm), lead (up to 5,350 ppm), mercury (up to 4.0ppm) and bismuth (up to 27.9ppm). The combination of these metals, in particular the high gold and silver at surface, make this prospect a very promising target with detailed work to continue to further delineate drilling targets.
An induced polarisation geophysical survey consisted of six lines totaling 10.2 line km using a dipole-dipole array. The results show two discrete chargeable zones at many times background levels, in the range of 40-60 mV / V over an area 700m x 300m in size. The chargeability anomaly is coincident with a moderate resistivity zone suggesting alteration and possible coincident quartz veining which continues at depth. The anomaly is open to the west and northwest from the survey area and follow up IP is planned to close off the anomaly. The chargeable zones provide additional strong support for further work at this prospect, in particular drilling. The IP chargeability parameter relates directly to the amount of metallic minerals in the earth and these anomalous results point to areas that are likely to contain anomalous amounts of metallic sulphide minerals such as zinc, lead and silver, consistent with that found at the Pirquitas deposit.
Artha's geological interpretation of the coincident geological, geophysical and geochemical anomalies at Pirquitas NW supports the view that the anomalies could be caused by the same hydrothermal system responsible for the mineralization in the Pirquitas mine and as such may be a satellite mineralized system from the Pirquitas deposit.
Positive exploration results to date have encouraged Artha to continue to conduct more exploration work on its Pirquitas properties. Artha is actively finalizing a community access agreement in order to begin an initial 2,500 meter drill program on the Noeilla Breccia and Pirquitas NW prospects.
