Hecla Mining Company today provided an update on its drilling programs during the first quarter.
There were up to 20 drills operating at 5 mines, all in North America.
- High-grade extensions defined two zones in the upper East and West Mines for potential new underground mining areas.
- The high-grade 113 Zone may link or intersect the western limit of the 118 Zone to define a significant resource area.
- Potential increase of oxide mine life through upgraded resource in the Middle Vein.
- Near-surface oxide mineralization defined at the new El Toro (South) over 5,000 feet along strike and from surface to 450 feet of depth.
- Expanding high-grade, near-surface resources at the East Ore and Upper Plate zones and upgraded resources in the NWW and Southwest zones in the central part of the mine.
- Drilling in the southern part of the mine on the 200 South Zone has upgraded resources and added to mineralized trends in that area.
- Some high-grade intersections at Fire Creek along trend of primary veins and new vein extensions identified.
- Underground drilling at Hollister has confirmed and expanded mineralization in the West Gloria and identified new mineralization to the north.
"We have been successful in discovering high-grade mineralization at Casa Berardi, San Sebastian, Greens Creek and in Nevada," said Mr. Phillips S. Baker, Jr., President and CEO. "Our focus at Casa Berardi is increasing underground reserves and as expected, we are seeing the underground resource continuing as the exploration moves east. In Mexico, the discovery of additional oxide resources at San Sebastian could extend the mine life. At Greens Creek we could see reserve increases again this year as the resources are upgraded. In Nevada, one of our main reasons for the acquisition is being proved with many high-grade intercepts."
Exploration (including corporate development) expenses were $4.4 million for the first quarter, a $3.0 million decrease over the first quarter of 2018. Exploration activities remained focused at Nevada Operations and at San Sebastian, Casa Berardi and Greens Creek.
Casa Berardi - Quebec
During the first quarter, up to six underground drills were used to refine stope designs, expand reserves and resources in the 113, 118, 123, 124, 128, 139, 152 and 160 zones and confirm further potential at depth and to the east and west (Figure 1). An aggressive underground drilling program has begun with the goal of upgrading and expanding resources in several promising areas and potentially extending the underground mine production. Up to three drills on surface completed in-fill and exploration drilling at the West Mine Crown Pillar (WMCP), the 128 Zone and at depth of the Principal Pit and the deeper potential below the 160 Pit (Figure 2). This drilling is concentrated on high-grade extensions below currently defined pits that could potentially be mined from underground or could expand the WMCP pit.
The 113 Zone has been a prolific historic mining center and recent underground development has provided a platform to evaluate the eastern-plunge of these high-grade lenses from the 1010-level within the West Mine. Initial drilling has been encouraging with intersections containing multiple structures with veins and strong alteration. There is potential at depth for the 113 Zone to intersect or link with the 118 Zone to the east.
High in the mine, drilling of the 118 and 124 zones from the 430-level continue to show the potential to extend and increase the grade in the Principal area. Recent drill intersections of the 118 Zone at 1200 feet from surface include 0.19 oz/ton gold over 15.3 feet and 0.53 oz/ton over 3.6 feet. At depth, drilling of the western extension of the 118 Zone from the 990-level exploration drift confirmed the continuity of multiple mineralized lenses to the west and at depth outside the current resource boundary. Recent intersections including 0.20 oz/ton gold over 9.8 feet suggest an extension of the resources of over 350 feet below the 1200-level.
Drilling of stacked, high-grade lenses of the 123 Zone is defining a connection between them over 1,900 feet of strike length and over 3,600 feet down-dip below the 1070-level (Figure 3). In the upper part of the 123 Zone, step-out drilling from the 750-level to the west shows the continuity of high-grade mineralization down-plunge for 400 feet and remains open to the west. Drilling has defined the east extension of the 124 Zone from the 430-level that is down-plunge of the Principal pit mineralization. Recent drill intersections below the 290-level include 0.19 oz/ton gold over 6.6 feet and continues to show the down-dip potential of the 124 lenses to the east and at depth.
Drilling below the proposed Principal Pit on the 128 Zone has defined a series of high-grade, steeply-plunging lenses that have been defined vertically for over 600 feet and extend from surface to below the 290-level (Figure 3). Drill intersections, including 0.24 oz/ton gold over 5.2 feet and 1.25 oz/ton gold over 1.6 feet, have extended the resource 300 feet and recent step-out drilling suggests the high-grade mineralization is open at depth and to the east. Further east, drilling of the 139 Zone south of the Casa Berardi Fault is showing mineralization is almost continuous between the West and East mines.
Exploration drilling of the 152 Zone at the west extent of the East Mine is evaluating the underground potential of the area between the 148 Zone and depth extensions of the 160 Zone. Intersections of 0.28 oz/ton gold over 2.8 feet and 0.17 oz/ton gold over 9.8 feet suggest the mineralization could link the zones together and provide additional deeper exploration potential. Underground drilling from the ramp at the 455-level, is currently targeting the down plunge of these results. Definition drilling continues at the 300-level of the East Mine to refine the depth extensions of the 160 Zone below the pit shells. Drilling has defined multiple lenses that include discrete quartz veins and massive sulfide styles of mineralization that contain good gold grades. This mineralization is steeply plunging to the west and is open to depth.
Drilling of the WMCP to evaluate the open-pit potential to the west of the West Shaft has upgraded the inferred resource to reserves that are part of a newly-defined open pit reserve announced with the year-end reserve update. The drill recent results also show that the near-surface, mineralized structures extends beyond the western extent of the WMCP pit and could result in an expansion of the pit.
In the second quarter of 2019, underground drilling in the West Mine is planned to evaluate the lower extensions of the 113 and 118 zones. Surface and underground drilling is expected to expand and refine the 124-128 zones closer to surface. In the East Mine drilling of the 148, 152 and 160 zones should refine and expand resources that have underground mining potential. These targets reflect the numerous opportunities (Figure 4) to extend mineralization defined in the pits, or near surface, to depth and potential underground mining.
More complete drill assay highlights from Casa Berardi can be found in Table A at the end of the release and a presentation showing drill intersection locations is available by copying and pasting the following URL into your Internet browser: http://ir.hecla-mining.com//interactive/newlookandfeel/4130678/Hecla_Q1-2019_ExplorationUpdate.pdf.
San Sebastian - Mexico
During the quarter, two core drill rigs and one reverse circulation (RC) drill operated at San Sebastian on surface. In addition, one underground drill rig completed in-fill drilling in the central and upper portions of the oxide zone along the Middle Vein. Surface exploration drilling was directed toward shallower oxide mineralization along the recently discovered El Toro (South) Vein and West Francine Vein (Figure 5). At the Middle Vein, in-fill drilling within the oxide (100, 101 and 104) zones intercepted vein intervals with similar grade and width to the previous exploration drilling results and will provide important data to guide stope design. Strong drill results include 206.5 oz/ton silver and 0.79 oz/ton gold over 6.1 feet and 49.8 oz/ton silver and 0.25 oz/ton gold over 6.7 feet. This drilling has upgraded resources and could add oxide mine life at San Sebastian.
The El Toro (South) Vein is located approximately halfway between the Andrea Vein resource area to the southeast and the Esperanza Vein to the northwest (Figure 5). Based on its location and orientation, this vein may represent the link between these two known veins with a total prospective strike length of over eight miles. Near-surface mineralization has been defined by core drilling for over 5,000 feet along strike and from surface to 450 feet of depth and includes intersections of 0.16 oz/ton gold and 24.1 oz/ton silver over 5.8 feet and 0.35 oz/ton gold and 21.4 oz/ton silver over 4.2 feet (Figure 6). Recent drill intercepts have identified veins that are up to 25 feet wide containing bands of sulfide mineralization. To the south, the El Toro vein has been fault-offset to the east and remains strong and open to the south. A new vein is located about 125 feet in hanging wall of the El Toro Vein and recent intersections include 0.26 oz/ton gold and 18.0 oz/ton silver over 9.5 feet. Recently one core rig has moved from the West Francine Vein to El Toro Vein to accelerate the drilling in this area.
At the West Francine Vein, located about 1,000 feet west of past drilling on the Francine Vein, recent drilling continues to intersect narrow, high-grade veins that has defined mineralization about 450 feet along strike. A recent drill hole at the eastern end returned narrow, high-grade intervals including 0.05 oz/ton gold and 70 oz/ton silver over 1.65 feet. Mineralization in this area is open laterally and at depth and follow-up drilling in this area is programmed later in the year. Drilling will continue during the second quarter to evaluate near-surface oxide mineralization at the El Toro (South) Vein area. An RC drilling program recently began to test geochemistry targets around the El Toro Vein discovery and along the Esperanza to Andrea Vein Corridor (Figure 7).
Separately, a bulk sample is proceeding on the polymetallic mineralization along the Francine Vein. The material from the bulk sample will be used for metallurgical studies and a viability test of the nearby Excellon Mill, where the processing of sulfide ores from San Sebastian is planned.
More complete drill assay highlights from San Sebastian can be found in Table A at the end of this release and a presentation showing drill intersection locations is available by copying and pasting the following URL address into your Internet browser: http://ir.hecla-mining.com//interactive/newlookandfeel/4130678/Hecla_Q1-2019_ExplorationUpdate.pdf.
Greens Creek - Alaska
At Greens Creek, drilling in the first quarter and strong assay results from previous drilling have upgraded and expanded the 200 South, East Ore, NWW, Upper Plate, 9A, and Southwest zone resources (Figure 8). In the East Ore Zone, intersections from drilling in the middle and the north end of the resource confirmed mineralization. Strong assay results included 20.52 oz/ton silver, 0.05 oz/ton gold, 4.20% zinc and 1.19% lead over 21.9 feet and 64.04 oz/ton silver, 0.27 oz/ton gold, 6.46% zinc and 2.36% lead over 7.6 feet (Figure 9). Drilling of targeted gaps between modeled ore zones intersected mineralization that compares well in thickness and location to existing trends. Mineralization is still open higher up in the mine. Drilling is planned to continue upgrading this resource throughout 2019.
Drilling of the 200 South Zone confirmed three flat-lying, high-grade lenses that are folded to the west and has enabled portions of bench mineralization below historic mining to be upgraded to an indicated resource category and potentially incorporated into the Life of Mine plan. Recent drilling included 6.87 oz/ton silver, 0.25 oz/ton gold, 15.70% zinc, 5.39% lead over 25.9 feet and 27.66 oz/ton silver, 0.42 oz/ton gold, 4.25% zinc, and 2.31% lead over 14.4 feet.
Near the mine portal elevation, drilling of the Upper Plate Zone to the northwest has defined at least two flat-lying zones that are folded to the east. Recent drill results include 42.15 oz/ton silver, 0.02 oz/ton gold, 10.84% zinc and 4.86% lead over 16.5 feet along the upper ore band and 93.59 oz/ton silver, 0.39 oz/ton gold, 4.95% zinc and 2.38% lead over 5.5 feet in the lower band. Definition drilling results indicate the upper and mineralization horizon thickens toward the Southwest D Fault from the east and the lower horizon extends up to 150 feet further than modeled also towards the Southwest D Fault.
Drilling continued at the southern end and lower portion of the NWW Zone, filling in a gap between the two ore zones. Results from recent drilling include 29.90 oz/ton silver, 0.16 oz/ton gold, 4.89% zinc and 2.74% lead over 11.4 feet and 16.87 oz/ton silver, 0.11 oz/ton gold,16.07% zinc and 9.41% lead over 7.2 feet. The drilling shows the mineralization is generally contained within argillites with a precious metal-rich zone identified west of the current resource and a base metal-rich zone (16-20% zinc) extending beyond the current resource. Drilling of the NWW Zone will continue through the first half of 2019. Drilling north of the Southwest Zone targeted an area between the Southwest and NWW zones. Recent drill results include 77.18 oz/ton silver, 0.57 oz/ton gold, 8.05% zinc and 3.94% lead over 7.5 feet and 94.33 oz/ton silver, 0.40 oz/ton gold, 12.22% zinc and 4.83% lead over 7.0 feet suggest possible continuity of high-grade mineralization between the current resources.
Definition drilling in 2019 will focus on the East Ore, Northwest West, and 9A zones. Exploration drilling in 2019 will target the southern extension of the 200 South Zone and the Deep Southwest. Definition drilling in 200 South Zone is planned to continue to mid-2019 and drilling of the Upper Plate has stopped but is expected to resume in the fourth quarter.
More complete drill assay highlights from Greens Creek can be found in Table A at the end of this release and a presentation showing drill intersection locations is available by copying and pasting the following URL address into your Internet browser: http://ir.hecla-mining.com//interactive/newlookandfeel/4130678/Hecla_Q1-2019_ExplorationUpdate.pdf.
The 2019 underground drill program at Fire Creek is designed to upgrade and expand resources at Spirals 2, 3, 4 and 9 and the Titan and North zones (Figure 10). There were up to four drill rigs operating underground at Fire Creek in the first quarter with definition drilling focusing the southern up-dip of Spiral 2 of the Vein 39 and Joyce mineralization in advance of sill development, on upper portions of Spiral 3 along the Honey Runner, Karen, Hui Wu and Joyce structures, and the lower and upper portions of Spiral 4. The focus of the drilling was to upgrade resources as underground exploration drilling is anticipated for later in the year.
The Spiral 2 drilling targeted the up-dip, southern extents of Vein 39 and Joyce veins. Drilling on Vein 39 encountered strong alteration in the structures but overall weak assays. The Joyce program identified continuous veins with moderate grades, but the best results occurred along Vein 40 which is a ladder vein between Vein 39 and Joyce. Drill intersections of Vein 40 include 0.80 oz/ton gold over 7.5 feet and 2.24 oz/ton gold over 1.1 feet.
Drilling targeting up-dip veins in the Spiral 3 area intersected mineralization that is characterized by large, low-grade zones that contain narrow, high-grade structures with some continuity. For example, drilling along the Honeyrunner structure returned grades of 0.17 oz/ton gold over 30.7 feet that contained an interval of 0.40 oz/ton gold over 2.0 feet (Figure 11). Other intersections in Spiral 3 within strongly argillized basalts include 0.97 oz/ton gold over 5.0 feet (Vonnie Vein) and 0.27 oz/ton gold over 11.9 feet (Karen Vein). Drilling in the vein dominated zone was successful in upgrading the model in the 5350 timber raise area. Drilling from Haulage 3, in combination with mapping and channel sampling in the Spiral 4 development, indicate that mineralization of the Joyce, Vonnie and Vein 06 is along the margins of multiple north-striking, steeply-dipping dikes. Drilling to date indicates that this mineralization is dominated by a strong clay (argillite) alteration with semi-continuous, high-grade calcite/quartz veining in structural zones.
Drilling of the Joyce structural system continues beyond the modeled resource including high-grade drill intercepts such as 1.28 oz/ton gold over 2.2 feet and 1.11 oz/ton gold over 1.7 feet (Figure 12). Drilling on the Vonnie Vein had intersections including of 0.18 oz/ton gold over 11.1 feet and 0.29 oz/ton gold over 5.4 feet. Other veins not included in the life of mine intercepted 0.97 oz/ton gold over 0.7 feet and 0.76 oz/ton gold over 1.2 feet on Vein 3 and 0.26 oz/ton gold over 13.6 feet on Vein 64. Underground drill programs are proposed to upgrade resources and evaluate new targets throughout the mine (Figure 13).
Surface permits are being finalized to begin drilling on the Zeus, Kronos, Titan, Far View and Guard Shack targets to extend mineralization of known resources near the mine.
Up to two rigs were active in the West Gloria area during the first quarter with mine development and preparations proceeding to evaluate East Clementine and Hatter Graben (Figure 14). At West Gloria the drilling program from the end of the 5265-level targeted down-dip extensions of high-grade intersections of the Gloria Veins to the west and north (Figure 15). This drilling intersected parallel structures to the north of the Gloria Vein and confirmed that mineralization is stepping to the northwest as suggested by mapping of vent breccia/sinters on surface. Drilling below the level defined high-grade veins about 100 feet below high-grade intersections (0.32 oz/ton gold, 6.1 oz/ton silver over 11.6 feet) drilled late in 2018. In-fill and step-out drilling is planned to determine the continuity and extent of these higher-grade veins. Further east on the 5265-level drilling intersected mineralization (0.77 oz/ton gold and 10.9 oz/ton silver over 3.3 feet) about 60 feet above current workings. Additional drilling is planned in what is interpreted as the upward extension of an east plunging mineralized zone that is still open up-dip and to the west.
A long exploration drillhole to the north targeted interpreted structures north of the Gloria veins. Three zones of quartz-calcite veins and multiple intervals of crackle breccia and stockworks were intersected including an intersection of 0.38 oz/ton gold and 20.16 oz/ton silver over 2.5 feet. Near the end of the of the hole adularia alteration was observed which suggests proximity to epithermal mineralization. A second down-hole is planned to test below these intercepts.
Drilling is in progress on a 1,500-foot geotechnical hole in the Hatter Graben decline (Figure 16). The drill rig is then expected to drill exploration holes targeting the 181, 233, 234 and 243 veins. Definition drilling to upgrade resources in the West Gloria, 5190 Pump Chamber, East Clementine and 5278 areas has begun. Surface permits are being finalized to begin drilling to extend the Hatter Graben resource beginning in the second quarter.