TORONTO (miningweekly.com) – Copper explorer Copper Fox on Tuesday announced that its subsidiary Desert Fox had found elevated concentrations of copper and molybdenum at its Sombrero Butte project, located in the Bunker Hill mining district, north east of Tucson, Arizona.

Desert Fox Copper’s ongoing geochemical sampling and surface mapping programme had identified two large areas of elevated geochemical concentrations of copper and molybdenum, with vein controlled copper/molybdenum mineralisation, a coincident potassic/sericite alteration and sporadic tourmaline veining over a strike length of 4 km, which is open to the south west.

Area 1 was located in the north-west part of the 4-km-long zone and measured 1 000 m x 1 200 m, showing copper values associated with malachite, a copper oxide mineral, ranging from 76 parts per million (ppm) to greater than 2 450 ppm, and with molybdenum values ranging from 7 ppm up to 252 ppm. The area is open to the west.

Area 2, located in the south-east portion of the 4-km-long zone, measured 1 600 m x 2 800 m with copper values associated with malachite and chalcopyrite, a copper sulphide mineral, ranging from 76 ppm to greater than 2 450 ppm and with molybdenum values ranging from 7 ppm up to 489 ppm. This area is open to the south.

Desert Fox reported that three phases of cross-cutting porphyry dikes, and at least 15 new mineralised breccia pipes carrying abundant copper veinlets, were found within the two target areas, as well as extensive dickite (a hypogene clay mineral related to acid alteration under advanced argillic conditions in porphyry copper environments) alteration occured in a number of breccia pipes that appeared to form a halo surrounding Area 2.

"Our exploration target at Sombrero Butte is to find the source of the mineralised breccia pipes that occur within the property. The preliminary work to date has identified a mineralised trend that is open to the west and south west that hosts two large exploration targets with many features similar to a classical porphyry alteration-mineralisation model.

“These targets exhibit an outer limonite zone (interpreted to be due to oxidisation of pyrite) and an inner zone consisting of potassic/sericite alteration and sporadic tourmaline veining, vein controlled copper/molybdenum mineralisation and multiple mineralised breccia pipes; all positive features suggesting the existence of a porphyry copper/molybdenum environment,” Copper Fox president Elmer Stewart said in a statement.

He added that preparations for a deep penetrating geophysical survey were under way to collect chargeability, resistivity and magnetotelluric data over these target areas.

Copper Fox had spun out Desert Fox Copper, in August, to be the main operating vehicle responsible for acquisitions, exploration and development activities on the Van Dyke copper deposit and the Sombrero Butte copper project.

This followed joint venture (JV) partner Teck Resources assuming operatorship of the Schaft Creek project, in British Columbia, reducing the company’s level of activity at the project, which up to that time was its main focus.

Teck and Copper Fox in July announced that they had formed a JV to further explore and develop the Schaft Creek polymetallic project, in which Teck would hold a 75% interest and become the operator of the project, with Copper Fox owning the remaining 25% and receiving $60-million in three payments.