The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Placer gold miner explores antimony rich deposit at its Nolan Creek Mine where large placer nuggets are being recovered
With gold nuggets weighing up to 41 troy ounces, Silverado Gold Mines Ltd's Nolan Placer Gold Mine is the type of place that would give even the well-seasoned miner gold fever!
Located about 280 miles, or 452 kilometers, north of Fairbanks, Nolan Creek has placer ore that does not thaw sufficiently to be processed until mid-June. During the ensuing three months, crews work around the clock, sluicing as much ore as possible before subfreezing temperatures return to the Arctic.
From June to Aug. 31, 2007, Silverado ran more than 18,000 yards of gravel through its sluice plant, recovering 3,726 ounces of gold in the process. Of the gold recovered, 2,811 ounces were nuggets weighing between 0.1 ounce and 18.32 ounces.
The company built the processing plant it now uses at Nolan Creek and first put it into operation in 2006. A gravity-water plant that has the capacity to process 420 yards of gold-bearing gravel during two 11-hour shifts, it contains a sluice box modified to be more efficient in collecting large nuggets that are common at Nolan Creek.
Crews go underground for the winter
Though temperatures eventually get too cold for sluicing, mining operations continue at Nolan Creek. During winter months, Silverado employs crews around the clock in stockpiling gravels mined underground for processing the following summer.
Material processed last summer was stockpiled from underground mining at Mary's East and Swede Channel the winter of 2006-2007. Samples were taken during each shift out of the sides of the tunnel to obtain an estimate of the gold content of the ore being stockpiled. One of the samples taken from the Mary's East deposit in February 2007 produced a 13.78-ounce nugget.
Searching for the hardrock source of nuggets
The real treasure at Nolan Creek may not be in nuggets found in the ancient channel but in the lode source of those nuggets.
Much of the gold found during placer operations at Nolan Creek has been crystalline in nature, and because gold is such a soft mineral it only occurs in crystal form if it is at or very near the lode source.
Vancouver, B.C.-based Silverado concluded that the large nuggets they are finding in the valley originated in the five-mile-long Solomon shear zone, which runs along the east side of Nolan Creek.
The company completed 920 feet of trenching on the Pringle bench, part of the Solomon shear zone, during its 2006 fall exploration program, and was able to confirm that the Solomon shear, in fact, contained high-grade lode gold, the company said. Samples also revealed a significant amount of antimony. Silverado intersected three separate zones containing antimony-gold-quartz veins.
Encouraged by results of the trenching in 2006, the company continued to explore the Pringle bench. In zone one, Silverado intersected a 16.4 foot/ 5 meter section that assayed at 5.22 ounces of gold per ton and contained 8.74 percent antimony.
The company purchased a diamond drill rig to further investigate the discoveries. A total of nine holes were drilled in Pringle. Assay results are still pending from the Pringle drill program.
The drill rig moved on to Workman's bench, about one-quarter mile southwest of Pringle. Seven holes, totaling 2,149 feet were drilled in Workman's bench in 2007. Samples show drill hole 07SH01 had a 19-foot intersection with gold grades of 2.69 grams per metric ton and 3.24 percent antimony. This included a 6-foot intersection grading 6.55 grams gold per metric ton and 8.81 percent antimony. Drill hole 07SH15 also had a 6-inch intersection with gold grades of 19 grams per metric ton and 34.51 percent antimony.
Tunneling under Workman's Bench
Crews at Nolan began tunneling under Workman's bench late in 2007. The tunnel, which continues from an area previously mined by Silverado, will burrow into an 80-foot-wide mineralized zone discovered during drilling conducted earlier last year.
Once the tunnel reaches this mineralized zone, it will first follow the lode mineralization south and then will follow the zone north toward Pringle.
Siverado Gold Mines CEO and President, Garry Anselmo told Mining News that further exploration will be needed before the company decides on the best method of processing the hardrock ore recovered at Nolan Creek. Options being considered include setting up a processing plant on site, shipping the ore to the company's antimony-rich Eagle Creek property outside of Fairbanks, or having it processed at Kinross Gold Corp.'s mill at True North.
Silverado has purchased a loader designed for underground tunneling. The Australian-made loader had a price tag of $1 million, but Anselmo said the company was able to purchase it for $555,000, and delivery is expected in about five months.
This equipment meets all U. S. regulations and will assist the company in its underground mining, he added.
Exploring Fortress
Silverado began exploration at an area known as Fortress located about two miles, or 3.23 kilometers, northeast of Pringle along the Solomon Shear. Karsten Eden, the company's vice president of exploration, first discovered a gold-bearing outcrop at the Fortress formation in 2000.
An electro-magnetic survey performed in 2007 revealed a gold and arsenic anomaly more than 1,500 feet long. Geophysical and geochemical work also revealed a gold-bearing antimony-quartz vein system on the Saddle, located in the southern Fortress area.
Silverado plans to explore further at Fortress in 2008. Anselmo told Mining News that the company will further define Fortress with additional geochemical and geophysical work before starting a drill program.
Silverado has added to its mineral claims at Nolan Creek by acquiring 13 federal placer claims and 237 federal lode claims, increasing total holdings to more than 11 square miles, or nearly 18 square kilometers of area. The company now holds 342 federal lode and 218 federal placer claims in the Nolan Creek land package.
Eagle Creek gold/antimony property
Silverado's Eagle Creek property, located about 10 miles, or 16 kilometers, north of Fairbanks, is Alaska's second-largest producer of antimony, a silver-white crystalline mineral used in a wide variety of alloys.
The company launched production and sales of antimony from Eagle Creek in the late 1980s. Though the company's original interest in the property was antimony, consistent discoveries of gold soon led to the conversion of Eagle Creek into a gold-antimony property for Silverado.
Several discoveries on the property suggest there is a significant hardrock gold deposit on the property that Silverado plans to pursue with future exploration.
Historic Ester Dome property
Silverado has owned its Ester Dome gold property 10 miles northwest of Fairbanks since 1978. The creeks in the Ester Dome area were first mined in the early 1900s and have historically produced more than 4 million ounces of placer gold.
In 1984 Silverado, in partnership with another mining company, built the 300-ton-per -day Grant Mill. The mill operated until 1989 and produced 15,305 ounces of gold and 8,231 ounces of silver.
From 1990 and 1993, the company continued surface exploration on the property and drilled 45,162 feet. In 1999 Silverado focused its resources on the Nolan Project and reduced its holdings at Ester to 2.5 acres, which includes the Grant Mill.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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