Status: Available for Option
IOCG style gold and copper associated with intermediate composition volcanic porphyry intrusives.
Location and Setting
The San Javier prospect lies within the Sonoran Cu-Mo-W Province and is located approximately 140 km east-southeast of Hermosillo Sonora, Mexico, near the village of San Javier. Access to the property is by paved two lane highway.
The project consists of one claim totaling 43.28 Ha, 100% owned by Millrock Resources.
A historic mine, La Trinidad, is approximately 600 meters east of San Javier. It is not known how much ore was produced, however, a stope is approximately 50 m long by 8 meters wide and historic maps show copper grades as high as 2.12%. Modern exploration began as early as the 1960s with drilling performed by Peñoles, and later by Phelps Dodge. In 2007, Constellation Copper Corporation defined an inferred resource of 81 million tons of 0.35% copper on the adjacent Cerro Verde deposits which has similar geology and mineralization to the San Javier property.
Mineralized and iron stained Upper Cretaceous Tarahumara volcanic rocks overlie thick (up to 3,150 m) Triassic Barranca Group sequences of sandstones, conglomerates, siltstones, and shales containing coal horizons. The Barranca Group rocks are intruded by Upper Cretaceous to Tertiary diorite and later by Oligocene rhyolite to andesite porphyry.
Structure and Alteration
The area is structurally complex with strike slip faulting, compressional faulting and folding followed by extensional tectonics. The property contains abundant veining, low angle faults, and well defined normal faults oriented NS and NW-SE. Each of the faults may have influenced the formation of breccias containing hydrothermal alteration and mineralization. Alteration minerals consist of an assemblage of sericite, carbonate, hematite, silicification and less common pyrite.
The most significant copper and gold mineralization at San Javier is in hydrothermal breccias and associated stockwork veinlets. The highest copper grades collected have been associated with specularite veinlets and copper oxides in andesite porphyry. Reconnaissance sampling and mapping results include twenty-two rocks of which eleven contain between 0.1 and 1.92 ppm Au and twenty-one containing 48 to 739 ppm Cu.
Conclusions and Recommendations
San Javier is a prime exploration target located ~800 meters from the former Cerro Verde development project, in the heart of an area known for its abundance of mining prospects containing high gold, copper and silver grades. Rock chip samples collected during preliminary reconnaissance exploration and mapping have returned encouraging results. Recommendations include regional and detailed structural mapping, rock, stream sediment and soil sampling and ground geophysics. These methods are aimed at determining the extent of mineralization, the structural controls on mineralization and at targeting future drill holes.
“THE TECHNICAL INFORMATION WITHIN THIS DOCUMENT HAS BEEN REVIEWED AND APPROVED BY GREGORY A. BEISCHER, PRESIDENT & CEO OF MILLROCK RESOURCES INC. MR. BEISCHER IS A QUALIFIED PERSON AS DEFINED IN NI 43-101.”