A 13.78 oz gold nugget has been found at Silverado Gold Mines’ Mary’s East underground workings in Alaska, USA, during sampling and grade control work. Gold nuggets of this size range are rare, and accordingly priced. The Nolan properties are famed for producing some of the largest gold nuggets ever found in Alaska. In addition to the big nugget, many other gold nuggets are being found and all of them are of jewellery quality.
As the tunnels are being advanced into the Mary’s East placer deposit, samples are systematically taken and analyzed by standard gravity methods to provide an estimate of the gold content of gravel being stockpiled during each shift of work. Two shifts of mining advance the tunnels seven days per week during the winter season. Placer gold deposits at Silverado’s Nolan Properties have a significant ‘nugget factor’, defined as the uneven distribution of larger sizes of gold particles and their influence on the overall valuation of the deposit. The tunnel walls are scanned at the interface of gravel to bedrock with a metal detector, using strict security procedures. This provides a good indication of gold nugget distribution, and helps guide the tunnel development between drillholes. Areas of very rich gold bearing gravel have been delineated, and are being stockpiled for sluicing during the summer of 2007. 24.26 oz of gold nuggets were recovered from 0.9 m3 of gravels in a recent test of an underground area that prior drilling had shown to be rich in gold.
Crews will continue to stockpile gold bearing gravel from the Mary’s East tunnels into early spring. 3,500 m3 of gravel from Mary’s East plus an additional 6,880 m3 of gravel from the Swede Channel. Processing the stockpiles for gold removal is expected to begin after the stockpiles are sufficiently thawed (mid June 2007). Thawing is critical, to ensure that all of the gold, from large nuggets down to the tiniest gold dust particles can be liberated from the frozen gravel chunks, then concentrated by gravity separation in our modern sluicing plant.
