Drilling expands Greens Creek ore zones

Hecla Mining Company Aug. 7 reported that drilling in the second quarter and strong assay results received from drilling in the first quarter have upgraded and expanded the Deep 200 South, Gallagher, East Ore, Upper Plate and Southwest Bench zone resources at its Greens Creek Mine in Southeast Alaska.

Drilling has extended the Deep 200 South Zone, especially to the south. One hole drilled in the southern portion of Deep 200 South cut eight feet (2.4 meters) averaging 101.4 ounces per ton silver, 0.09 oz/ton gold, 4.2 percent zinc and 2.1 percent lead. Hecla Mining said bench mineralization is confirmed to be present as two flat-lying, high-grade lenses that have been upgraded to an indicated resource.

Exploration drilling south of the current resource has extended 200 South Bench mineralization another 250 feet with a 23.6-foot (7.2 meters) intersection averaging 31.8 oz/ton silver, 0.01 oz/ton gold, 2.2 percent zinc and 1 percent lead.

Deeper drilling has defined a third, lower mineralized horizon along the mine contact that has been folded to depth relative to the bench mineralization. Recent exploration drilling to the south also identified thin bench mineralization outside the modeled ore zone to the west. Recent intersections in this area include three feet (0.9 meters) averaging 22.8 oz/ton silver, 0.38 oz/ton gold, 2.7 percent zinc and 1.3 percent lead. Shallow, east-dipping mineralization more than 250 feet west of the modeled ore zone includes a 9.2-meter (2.8 meters) intercept averaging 39.9 oz/ton silver, 0.02 oz/ton gold, 1.3 percent zinc and 0.7 percent lead. Hecla said current exploration drilling further south suggests the bench mineralization remains robust.

The Idaho-based miner also reports that drilling of the Gallagher zone confirmed modeled thicknesses and may have increased the resource and mineralization further to the west. Intersections from this program include 23.9 feet (7.3 meters) of 10.6 oz/ton silver, 0.04 oz/ton gold, 2 percent zinc and 1 percent lead. Exploration drilling also intersected ore lithologies (characteristics) along and west of the Gallagher Fault. Future drilling is planned to see if the current precious metal-rich mineralization transitions into broader and higher-grade precious and base metal-rich mineralization in this area.

Hecla said drilling of the Upper Plate zone suggests that there are two, flat-lying bands of ore near the mine portal elevation.

Drill results show the lower band of mineralization is similar in thickness to the resource model, although it occurs beyond the currently outlined resource to the west and south. South of the current lower band, step-out drilling has cut 24.1 feet (7.3 meters) averaging 42.9 oz/ton silver, 0.04 oz/ton gold, 3.1 percent zinc and 1.5 percent lead.

Hecla said the upper band is thicker than the resource model, including 20.8 feet (6.3 meters) 21 oz/ton silver, 0.02 oz/ton gold, 9.7 percent zinc and 5.8 percent lead. The company said recent drilling has extended this mineralization to the west and south, and drilling from surface in the third quarter could expand this resource further to the west and north.

Drilling of the Lower Southwest Zone indicates that a newly-defined lower ore band extends farther to the north and higher in elevation than modeled. Thick intercepts of white ores and massive sulfide lithologies continue to be found beyond the northern extent of the current resource. Recent drilling of the upper remnant limb of the lower Southwest Zone shows the mineralization in this section is much thicker than anticipated.

In the East Ore Zone, Hecla reports that intersections from definition drilling – including 24.1 feet (7.3 meters of 18.8 oz/ton silver, 0.24 oz/ton gold, 12.4 percent zinc and 4.7 percent lead – confirm previously modeled resource estimates, particularly at higher elevations.

For the balance of 2018, Hecla plans to focus underground drilling on the Deep 200 South, Gallagher, East Ore and Southwest Bench zones, with additional drilling targeting the Northwest West and 9A zones.

Hecla reports that the first three holes from the surface drill program at Greens Creek, which got underway in June, have intersected broad zones of stockwork veining and 3- to 5-foot wide bands of semi-massive sulfide containing significant sphalerite (zinc mineralization), galena (lead mineralization) and silver sulfosalts. This semi-massive sulfide zone is about 800 feet west of the current 200 South Bench resource and may represent part of a bench syncline that extends appreciably along strike to the north and south.

–SHANE LASLEY