Here is a description of one of their other projects taken off the website. It looks like it might be a good silver target.
Sierra Rosario Project, Sinaloa, Mexico
Sierra Rosario is an early stage exploration project that has returned very encouraging results from multiple zones of mineralization.
Sierra Rosario was acquired by staking in April, 2002 (see news release) and is Grupo Northair’s sixth project in Mexico. Sierra Rosario lies along the western flanks of the Sierra Madre Occidental geological province and covers at least six gold and silver occurrences discovered by Northair exploration staff as a result of the Company's ongoing generative exploration program.
The Sierra Rosario Project is located approximately 25 kilometers northwest of Choix, Sinaloa; and 40 kilometers east of Alamos, Sonora. Both towns have a strong mining history. The Company’s geologists were initially introduced to the area by local gambusinos who described drainages with rich placer gold. A roughly 1.5 kilometer stretch of a main drainage within the property contains dozens of historic placer workings, and most of the smaller arroyos within the southern portion of the property also contain placer gold. Gambusinos have also produced gold from soils and colluvium in this southern area which may overlie mineralized bedrock.
The property contains Cretaceous age limestone intruded by upper Cretaceous granodiorite belonging to the
Sinaloa batholith. These older rocks are locally overlain by a fine-grained silicic volcanic unit that hosts much of the mineralization. The volcanics have been intruded by numerous phases of granodiorite dikes, dacite porphyry and rhyolite porphyry. The age of the volcanics and younger intrusives is interpreted as being lower Tertiary. Although the granodiorite dikes are intensely altered, mineralization appears to be more related to the dacite and rhyolite porphyries. The property is intersected by numerous regional deep seated fault systems of variable orientation, some of which are important conduits for localizing mineralizing fluids.
Three deposit types have been identified to date:
1. Disseminated and structurally controlled Ag-Au (+Cu, Pb, Zn) in altered rhyolite porphyry
2. High sulfidation, structurally controlled gold in volcanic and dacite porphyry
3. Polymetallic mantos replacements in limestone
The “San Rafael Zone” is the principle target defined to date, and occurs in an intensely altered rhyolite porphyry in the northern part of the concession. An exploration program was recently completed (see news release) on the San Rafael Zone. The program, consisting of geologic mapping and sampling, has shown the known surface expression of the San Rafael Zone of mineralization to be approximately 200 x 70 meters within an intensely altered rhyolite porphyry. Mineralization is epithermal, and contains strong silica replacement and quartz veining with multiple orientations. Only about 20% of the zone is exposed in workings and outcrops, limiting the ability to thoroughly sample the zone without a mechanical trenching program, although there are numerous small “open pits” and several small adits made by local miners within the zone. Most samples taken by the Company were 5 meters in width but range from 3 to 7 meters. An effort was made to orient samples perpendicular to the strike of mineralization using standard industry accepted sampling techniques. Where possible, sampling was continuous channel samples for composite averages, however this attempt was constricted due to limited outcrop. Sample weights averaged approximately 2.5 kg, with assaying performed by ALS Chemex Labs, Inc. The average for the twenty-three samples taken is 181 g/t silver and 0.321 g/t gold with anomalous copper, lead and zinc values.
Five additional zones of structurally hosted gold mineralization have been identified within the property. These zones are associated with dacite porphyries and have been interpreted as a primary source of much of the placer gold. True widths of these mineralized zones are generally difficult to determine due to a thin veneer cover of soil and colluvium, but surface expression of alteration frequently exceeds 20 meters. A total of 26 samples have been taken from these five zones, with eleven samples reporting greater than 100 ppb gold and a high of 5.48 g/t. Assaying indicates the presence of coarse free gold with a strong nugget effect
