Mining and exploration review north of the 60th parallel

Sliver as Good as Gold – Greens Creek’s ore production is unearthing all kinds of metals on a silver platter.

14 - DSC2467One of the world’s largest silver mines, Hecla Mining’s Greens Creek is also the only active mine with part of its operations inside a United States National Monument. Having produced 7.4 million ounces of silver last year, 2014’s production is anticipated to be around the same at between 6.5 and 7.0 million ounces, with a “golden lining” of 55,000 ounces of gold to be produced.

The outlook for 2015 and beyond is promising with the mine having a projected life of another nine years. The proven and probable reserves for Greens Creek are 92.5 million ounces of silver, 713,000 ounces of gold, 256,130 tonnes of lead and 677,940 tonnes of zinc. Mike Satre, manager of Government and Community Relations at Hecla Greens Creek Mining Company explains how “proven and probable reserves” are tested for.

“It’s a simple question with a very complex answer, however in the simplest of terms: drilling information is used to create geologic models of the ore deposit.  As more drilling occurs, the higher the confidence in the models.  Once sufficient drilling has occurred, economic parameters are applied to the models so that engineered plans can be created in the areas that are profitable to mine.  The material selected in the mine plans become ‘ore’ and are then officially accounted for in the mine’s reserves,” he states.

Satre shares the second quarterly report for 2014, “At Greens Creek, definition and pre-production drilling continued to upgrade the 5250, West Wall, and Deep Southwest resources. Drilling of the Deep 200 South confirmed the resource model and shows the upper limb of the bench fold extends up to 150 feet east beyond the current model. Drilling of the bench mineralization provided some of the widest and highest grade intercepts in recent history at the mine. Significant drill intersections include 85.1 oz/tonne silver, 0.18 oz/tonne gold, 10.2 per cent zinc, and 4.8 per cent lead over 12.9 feet, and 44.3 oz/ton silver, 0.40 oz/ton gold, 23.1 per cent zinc, and 12.4 per cent lead over 3.2 feet. Drill intersections at the Deep 200 South continue to be very encouraging and mineralization remains open to the south.
Three surface drills were positioned in the south, middle, and north regions of Killer Creek in mid-June to follow up on broad zones of high-grade copper, silver, lead and zinc stockwork mineralization defined by surface drill programs in 2012 and 2013. This program should better define the extents of copper and silver-zinc rich stockwork mineralization and evaluate the deeper mine contact.”

14 - DSC0555Greens Creeks’ mine lies on 17 patented federal mining claims and they are all 100 per cent owned by Hecla.

“We lease lands from the United States Department of Agriculture’s Forest Service for our surface facilities including the mill facility, admin offices, equipment shops and our dry stack tailings facility,” explains Satre.

They also have rights to land above ground.

“In 1995, an act of congress allowed us to facilitate a land exchange whereby we purchased and conveyed private lands in Admiralty Island to the federal government. In exchange we received exclusive mineral rights to approximately 7,400 acres immediately surrounding the mine.  In addition, we hold numerous unpatented federal mining claims to the north of the land exchange boundary,” says Satre.

While none of the underground mine site falls within the National Monument boundaries, their tailings facility and part of their road are inside Admiralty Island National Monument.

An underground operation where they mine 2,200 tonnes of ore a day, they also have a presence above ground. Satre continues, “[The] total surface impact [of the mine] is about 350 acres, approximately 45 per cent of which is the mine access road.” Once brought to the surface, the mined ore is “shipped to a variety of smelters around the world for refining, [where the metals are extracted from the concentrates we have produced]”.

Located approximately 15 miles south of Juneau, Greens Creek is found in Southeast Alaska on Admiralty Island. With only one permanent settlement on the island – Angoon, a small village 50 miles south of the mine – the island sees quite a jump in its population every day when around 200 of Greens Creek’s approximately 415 employees (mining and underground support, mill workers, surface support and administrative staff) are shuttled to the island on Hecla’s 35 minute ferry ride. The mine is mostly staffed locally. Satre shares, “75 per cent of the workforce is Alaskan, 55 per cent of the workforce lives in Juneau, 10 per cent live in other Southeast Alaska towns, 10 per cent live in other parts of Alaska, and 25 per cent live in the lower 48 states.”

Hecla operates its mine all year round, and for some, that means not seeing daylight for a couple of weeks a year. The entrance to the mine, along with the administrative, mill, and maintenance buildings are at the 920 site – so named for its elevation from sea level – and this area doesn’t see direct sunlight for a few weeks every year around the winter solstice (December 21) . Workers go in when its dark, and emerge from the depths at the end of their shift when its dark, undoubtedly happy to see a little sparkle in their day thanks to the silver they’re unearthing.

Such harsh conditions might pose a threat to the work force on the small Alaskan island, if Hecla didn’t feel an obligation to do what they can to develop and maintain their employees. “We have committed to developing a skilled local workforce through funding of the Mine Training Center at the University of Alaska Southeast, ([having contributed] $600,000 since 2011), Engineering and Geology Scholarships at University of Alaska Anchorage and University of Alaska Fairbanks, as well as internal training programs that build skills and allow for upward mobility of all workers,” happily reports Satre.

Now one of the top 10 silver producing mines in the world, the mineralized outcrops for this mine were discovered by geologists back in 1974, underground drilling began in 1978 and the mine was opened with first production of metals in 1989. There was no production at Greens Creek between 1993 and 1996 but other than that, the mine has continued to satisfy Hecla with a history of exploration success and replacement of reserves.

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