How much copper, gold and silver have been identified so far at the Island Mountain deposit? Thanks to Brazil Resources Inc., the new owner of the expansive Whistler property in Southcentral Alaska, we have the answer to this question which has lingered for the past five years.
According to a maiden resource published April 18, Island Mountain adds 1.56 million ounces of gold, 3.34 million oz. of silver and 125.7 million pounds of copper to resources already identified at Whistler.
"”We are pleased to report this maiden NI 43-101 resource estimate for the Island Mountain deposit, which builds on the multimillion-ounce (gold-equivalent) resource we announced on the Whistler deposit last year,” Brazil Resources President and CEO Garnet Dawson said.
Re-evaluating Whistler
Since acquiring Whistler from Kiska Metals Corp. in mid-2015, Brazil Resources has poured over the results of extensive historical exploration carried out across the roughly 65-square-mile (168 square kilometers) property.
The Vancouver-based junior started this investigation with a re-evaluation of Whistler’s namesake deposit, which was discovered by Cominco Alaska in the late 1980s and further delineated by Kennecott Exploration, Geoinformatics Exploration Inc. and Kiska Metals.
According to an updated estimate prepared for Brazil Resources and published in September, the Whistler deposit hosts an indicated resource of 79.2 million metric tons averaging 0.51 g/t (1.28 million oz.) gold, 1.97 g/t (five million oz.) silver and 0.17 percent (302 million lbs.) copper; and an inferred resource of 145.8 million metric tons grading 0.40 g/t (1.85 million oz.) gold, 1.75 g/t (8.2 million oz.) silver, 0.15 percent (467 million lbs.) copper.
When you calculate the value of the gold and silver, this comes to 2.25 million gold-equivalent-ounces in the indicated category and 3.25 million gold-equivalent-ounces inferred.
This mirrors a resource calculated for Kiska in 2011.
“We are pleased to report this multimillion-ounce (gold-equivalent) resource estimate for the Whistler deposit from a very small portion of our 170-square-kilometer, 100 percent-owned project,” Dawson said at the time.
Quantifying Island Mountain
While much was already known about the Whistler deposit and the updated resource posed no surprises, the Island Mountain deposit had yet to be formally quantified with an independent NI 43-101 resource calculation.
Located some 14 miles south of the Whistler deposit, Island Mountain was discovered by Kiska in 2009.
IM-09-001, the discovery hole at Island Mountain, cut two distinct mineralized zones. The upper 150 meters – averaging 0.72 g/t gold, 2.37 g/t silver and 0.16 percent copper – is similar to the mineralization found at the Whistler deposit. The lower 106.9 meters of the hole averaged 1.22 g/t gold, 0.69 g/t silver and 0.05 percent copper.
Incorporating 34 of the holes (12,668 meters) drilled by Kiska, Island Mountain is estimated to contain 25.75 million metric tons of indicated resource averaging 0.53 grams per metric ton (438,000 ounces) gold; 1.16 g/t (960,000 oz.) silver; and 0.06 percent (34.07 million pounds) copper. Additionally, the deposit hosts 69.23 million metric tons of inferred resources averaging 0.51 g/t (1.12 million oz.) gold; 1.07 g/t (2.38 million oz.) silver; and 0.06 percent (91.59 million lbs.) copper.
This equates to 444,000 gold-equivalent-ounces in the indicated category and 1.13 million gold-equivalent-ounces inferred.
The deposit outcrops on the southwest slope of Island Mountain and has been drilled over a strike length of 300 meters and to a depth of 450 meters. Brazil Resources says the deposit is open to depth and some 400 meters to the north.
Hidden targets
While resources have been calculated for the outcropping Whistler and Island Mountain deposits, numerous other hidden targets have been identified on the expansive property.
“In addition to the Island Mountain and Whistler deposits, there are several other porphyry centers –Raintree West, Raintree North, Raintree South, Rainmaker and Cirque – with mineralized intersections similar to these deposits,” said Dawson.
While the Whistler deposit outcrops on a ridge, the Raintree and Rainmaker discoveries are largely covered with a 10- to 15-meter layer of glacial till in the valley below, making the underlying geology tough to discern from the surface.
Located some 1,800 meters east of the Whistler deposit, Raintree West has the most drilling of the Whistler orbit prospects.
Like all of the blind prospects at Whistler, Raintree West was first identified with airborne geophysics. Drilling in 2008 and 2009 identified two zones of mineralization. Both of these zones were intersected in hole WH09-002, which cut 128.7 meters of 0.56 g/t gold and 0.16 percent copper from a depth of 59 meters; and 40 meters of 0.98 g/t gold and 0.21 percent copper from 429 meters.
Drilling at Raintree North, Raintree South and Rainmaker has identified porphyry copper-gold mineralization similar to Raintree West.
Closing a C$4.5 million financing in March, Brazil Resources has the cash to advance Whistler as well as its copper-gold projects in Brazil. While the exploration company has yet to announce it plans for Whistler in 2016, it has provided a glimpse of its planned approach to the Alaska asset.
“Future drill programs will focus on delineating higher grade, near-surface zones at the Whistler and Island Mountain deposits, expanding their existing resource, and developing a better understanding of the size potential of nearby targets,” Dawson explained.
The junior is also shopping for other projects to complement its portfolio.
“In conjunction with advancing our existing project portfolio, the company continues to evaluate resource-stage projects in the Americas for potential acquisition,” the Brazil Resources CEO added.
