Mining News: News Nuggets: Drilling replaced silver, gold mined at Greens Creek in 2016
Hecla Mining Co. Feb. 22 reported that its 2016 exploration program successfully replaced the 11.9 million ounces of silver and 79,150 oz of gold mined at its Greens Creek Mine in Southeast Alaska last year, leaving reserves of both precious metals virtually unchanged. Greens Creek ended 2016 with 7.59 million tons of reserves averaging 11.7 oz/ton (88.87 million oz) silver; 0.09 oz/t (673,000 oz) gold; 7.6 percent (576,130 tons) zinc; and 2.9 percent (217,280 tons) lead. Roughly 8.3 million oz of silver and 46,500 oz of gold were added to reserves in the 9A and NWW zones during 2016. Additionally, Hecla increased measured and indicated resources increased in the 9A, NWW, SW, Gallagher zones, and the newly established Upper Plate zones last year. Definition drilling at Greens Creek continues to refine the resources of the 9A, Southwest Bench, East Ore and NWW zones for expected conversion to reserves. Exploration drilling has concentrated on the Gallagher Zone and Mine Syncline, a new exploration target area where the mine contact has been identified, at the north and southcentral parts of the mine. During the fourth quarter three drills were operating underground. Drilling of the southern extension of NWW continues to define mineralization along the lower fold. Highlighted intercepts include 18.6 feet of 45.4 oz/t silver, 0.20 oz/t gold, 19 percent zinc and 10.3 percent lead; and 10 feet of 51.7 oz/t silver, 0.20 oz/t gold, 11.2 percent zinc and 4.8 percent lead. Drilling also targeted the Upper Southwest (USW) zone around previously mined levels and identified mineralization that extends down to the upper limb of the NWW. Assay results of the USW include 10.2 feet averaging 46.8 oz/t silver, 0.03 oz/t gold, 10.9 percent zinc and 6.1 percent lead. The drilling has also identified shallow mineralization east of the Kahuna Fault and extends 100 feet in length and is open to the north. Recent drilling of the lower 9A zone has generally confirmed and upgraded the resource model particularly along the upper contact. Initial definition drilling of the East Ore zone shows that overall the mineralization is thinner than expected compared to the model, but this drilling is now advancing into the stronger mineralized portions of the resource to the north and south. Exploration drilling of the Gallagher zone at the southwest corner of the mine targeted a new flat-lying area that may define a mine contact that steepens to the east near the Gallagher fault. Deep exploration drilling of the Mine Syncline at the north end of the mine has shown that the mine contact continues steeply down-dip from the NWW zone and could define a broad syncline, or fold in the rock, below the current mine infrastructure that could host mineralization. Hecla said the early stage drilling here has identified some large prospective areas below the current mining that contain mine horizon.