The joint venture, dubbed the Red Cliff project, covers a 780-sq.-km area that extends across the Bonavista Peninsula and south to Bull Arm. The Red Cliff project includes Cornerstone’s Red Cliff, Fry’s Pond, Indian Arm, Trinity Pond and Smith South properties, totalling 117 sq. km, as well as 663 sq. km staked by the joint venture.
The package covers the Crown Hill Formation and related rocks of the Late Precambrian Musgravetown Group, which were recently identified by Cornerstone as having potential to host copper-silver mineralization.
Last fall, Cornerstone discovered a gently dipping, coastal exposure of stratiform copper-silver mineralization at Blue Point on its Red Cliff property. A total of 51 consecutive chip samples, each measuring half a metre in length, returned an average grade of 0.54% copper and 7.2 grams silver per tonne over a true thickness of 25.5 metres. Higher-grade sections included 0.93% copper and 13.02 grams silver over 13.5 metres.
A copper-cobalt-silver-in-soil anomaly lies directly along strike, 200-300 metres west of Blue Point. The 700-metre-long anomaly is highlighted by copper values of up to 588 parts per million and silver values of up to 6 ppm. The Blue Point mineralization occurs on the Bonavista Peninsula, 1.5 km northeast of the town of Duntara. Cornerstone reports that mineralization identical in style and setting occurs a further 10 km along strike to the west, near Tickle Cove.
‘Greybed’ horizon
Rocks in the Duntara area are dominated by thick sequences of gently to moderately dipping red conglomerates and sandstones. The mineralization at Blue Point and Tickle Cove is hosted in a 20-metre-to-possibly-40-metre-thick “greybed” horizon consisting of mainly fine-grained sandstone interbedded with fine-grained siltstone. These beds are reduced, giving them the “greybed” appearance. Upper and lower contacts with the redbed sequences are generally sharp but with some mixing.
The mineralized horizon is internally zoned, featuring a fine-grained brown zone measuring 8.5 metres thick, which sits roughly in the middle of the greybed. This zone returned an average grade of 0.97% copper and 17.01 grams silver across 8.5 metres.
The mineralization consists mainly of disseminated and (to a lesser degree) fracture-controlled chalcocite occurring as minute grains in the matrix of the sedimentary rocks. Cornerstone says the mineralization is usually only recognized by the presence of malachite on fresher broken surfaces and (to a lesser degree) on weathered surfaces. The coastal exposure may have undergone some leaching of copper, given the strong vertical cleavage and exposure to seawater.
Follow-up reconnaissance prospecting and soil sampling on the Red Cliff property have yielded additional anomalous prospects scattered over a 5-km distance from the Blue Point showing.
The Trinity Pond property was staked after company field personnel discovered sediment-hosted mineralization while carrying out reconnaissance prospecting. Hampered by early snow cover, limited grab sampling has yielded values of 1.06% copper and 5.5 grams silver.
Noranda has funded the staking of the additional 663-sq.-km package comprising 2,651 claims, and can earn a 51% interest in the total project area by spending $4 million and paying a total of $200,000 over four years. The major can increase its interest to 75% by completing a feasibility study.
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