The Hollister Mine (Ivanhoe Mining District), which Hecla acquired in July 2018, is located in Elko County, approximately 130 km (~80 mi.) northeast of the town of Winnemucca, Nevada and 29 km (~18 mi.) southeast of the Midas Mine.
The Hollister Mine is a large, very well preserved low-sulfidation, epithermal gold-silver deposit associated with mid-Miocene bimodal volcanism of the NNR. Over 115,000 ounces of volcanic-hosted, low-grade gold were extracted from 2 open pits. Later drilling led to the discovery of blind, high-grade veins in the Valmy Formation, Paleozoic basement rocks, which have produced >450,000 ounces of gold and >2.5 million ounces of silver from ore averaging ~34 g/t Au (1.00 opt) and 200 g/t Ag (5.83 opt) from cut-and-fill and longhole stoping since 2007. Typical epithermal vein textures are displayed at Hollister, most commonly massive, banded, bladed quartz, and vein breccias. Other features spatially related to the highest grades include the presence of banded quartz, bladed quartz, and alunite.
The mine is located along the Northern Nevada Rift (NNR) which is a major, north-northwest to south-southeast trending structural feature that that extends for at least 300 miles, from south-central Nevada to the Oregon-Nevada border. This is on trend with the north-western end of the Carlin Trend, which is approximately 5 miles wide and 40 miles long. Mineralization is related to the Miocene period of magmatic activity associated with the NNR while gold mineralization on the Carling Trend has been dated to late Eocene/early Oligocene magmatism.
Epithermal disseminated gold mineralization is hosted in volcanic tuffaceous units, andesites, and the Ordovician Vinini Formation. High-grade gold and silver mineralization is hosted as banded quartz veins in a group of near-vertical faults and fissures that trend west-northwest to east-west. The amount of displacement across these faults is small and their strike continuity varies between one hundred to several thousand feet. Primary lithologies in the area have been strongly altered by hydrothermal fluids with large areas of chalcedonic replacement bodies at the paleo water table in addition to sinter deposits.
|(years ended December 31)|
Information with respect to proven and probable ore reserves, measured, and inferred resources is set forth below.
|Mineral Reserves (As of December 31, 2018 unless otherwise noted)|
|Proven (1,2, 3)||2||0.73||7.1||2||17|
|Total Proven & Probable Reserves||11||0.67||7.2||8||82|
|Total M&I Resources||239||0.76||3.2||182||770|
|Inferred Resources (6)||550||0.4||3.1||223||1,716|
(1) The term “reserve” means that part of a mineral deposit that can be economically and legally extracted or produced at the time of the reserve determination. The term “economically,” as used in the definition of reserve, means that profitable extraction or production has been established or analytically demonstrated to be viable and justifiable under reasonable investment and market assumptions. The term “legally,” as used in the definition of reserve, does not imply that all permits needed for mining and processing have been obtained or that other legal issues have been completely resolved. However, for a reserve to exist, Hecla must have a justifiable expectation, based on applicable laws and regulations, that issuance of permits or resolution of legal issues necessary for mining and processing at a particular deposit will be accomplished in the ordinary course and in a time frame consistent with Hecla’s current mine plans.
(2) Mineral reserves are based on $1200 gold, $14.50 silver, $0.90 lead, $1.15 zinc, unless otherwise stated.
(3) Recoveries at Hollister for gold and silver are 87% and 80%. Cutoff grade of 0.396 Au Equivalent oz/ton and incremental cutoff grade of 0.07 Au Equivalent oz/ton. Unplanned dilution of 10% to 17% and 5% mining loss included.
(4) Mineral resources are based on $1350 gold, $21 silver, $1.10 lead, $1.20 zinc and $3.00 copper, unless otherwise stated.
(5) Recoveries at Hollister for gold and silver are 87% and 80%. Au equivalent cutoff grade of 0.352 oz/ton. The minimum mining width is defined as four feet or the vein true thickness plus two feet, whichever is greater.
(6) Inferred resources for the Hatter Project at the Hollister Mine calculated using recoveries for gold and silver of 82.7% and 71.8% and an Au equivalent cutoff grade of 0.27 oz/ton.
Reporting requirements in the United States for disclosure of mineral properties are governed by the SEC and included in the SEC’s Securities Act Industry Guide 7, entitled “Description of Property by Issuers Engaged or to be Engaged in Significant Mining Operations” (Guide 7). However, the Company is also a “reporting issuer” under Canadian securities laws, which require estimates of mineral resources and reserves to be prepared in accordance with Canadian National Instrument 43-101 (NI 43-101). NI 43-101 requires all disclosure of estimates of potential mineral resources and reserves to be disclosed in accordance with its requirements. Such Canadian information is being included here to satisfy the Company’s “public disclosure” obligations under Regulation FD of the SEC and to provide U.S. holders with ready access to information publicly available in Canada.
Reporting requirements in the United States for disclosure of mineral properties under Guide 7 and the requirements in Canada under NI 43-101 standards are substantially different. This website contains a summary of certain estimates of the Company, not only of proven and probable reserves within the meaning of Guide 7, which requires the preparation of a “final” or “bankable” feasibility study demonstrating the economic feasibility of mining and processing the mineralization using the three-year historical average price for any reserve or cash flow analysis to designate reserves and that the primary environmental analysis or report be filed with the appropriate governmental authority, but also of mineral resource and mineral reserve estimates estimated in accordance with the definitional standards of the Canadian Institute of Mining, Metallurgy and Petroleum referred to in NI 43-101. The terms “measured resources”, “indicated resources,” and “inferred resources” are Canadian mining terms as defined in accordance with NI 43-101. These terms are not defined under Guide 7 and are not normally permitted to be used in reports and registration statements filed with the SEC in the United States, except where required to be disclosed by foreign law. The term “resource” does not equate to the term “reserve”. Under Guide 7, the material described herein as “indicated resources” and “measured resources” would be characterized as “mineralized material” and is permitted to be disclosed in tonnage and grade only, not ounces. The category of “inferred resources” is not recognized by Guide 7. Investors are cautioned not to assume that any part or all of the mineral deposits in such categories will ever be converted into proven or probable reserves. “Resources” have a great amount of uncertainty as to their existence, and great uncertainty as to their economic and legal feasibility. It cannot be assumed that all or any part of such a “resource” will ever be upgraded to a higher category or will ever be economically extracted. Investors are cautioned not to assume that all or any part of a “resource” exists or is economically or legally mineable. Investors are also especially cautioned that the mere fact that such resources may be referred to in ounces of silver and/or gold, rather than in tons of mineralization and grades of silver and/or gold estimated per ton, is not an indication that such material will ever result in mined ore which is processed into commercial silver or gold.
2018 Reserves & Resources PDF
At Hollister, the 32,286 tons processed at the mill for Hecla in 2018 contained approximately 11,779 ounces of gold and 106,056 ounces of silver. Reserves at Hollister are 7,600 ounces of gold and 82,400 ounces silver and are a reduction from the second quarter 2018 primarily due to mining depletion, but also due to removal of material because of thinner vein interpretations. Additional reserve reductions were made as a result of recent identification of fault offsets in the West Gloria area; this material may come back into the reserve once the structural geology and offset magnitudes are interpreted and drill tested. Measured and indicated resources are 181,900 ounces of gold and 770,200 ounces of silver and inferred resources are 222,700 ounces of gold and 1.7 million ounces of silver.
Up to three rigs were active in the West Gloria, East Clementine and Gwenivere areas during the fourth quarter of 2018. The West Gloria drilling program from the end of the 5265 Level targeted the extension of the Gloria veins to the west where previous drilling had identified veins. Drill results along the West Gloria structure below the level define numerous high-grade veins including 0.32 oz/ton gold and 6.1 oz/ton silver over 11.6 feet and 0.25 oz/ton gold and 10.2 oz/ton silver over 5.5 feet. Additional in-fill drilling is required to determine the continuity of these higher-grade veins. The East Clementine program targeted up-dip extensions of the 233 and 243 veins to follow up on high-grade intersections near the unconformity. Three intercepts, including 1.78 oz/ton gold and 7.5 oz/ton silver over 1.7 feet, on the 233 Vein have delineated a mineable resource close to current workings on the 5190 level. Another intercept, 0.60 oz/ton gold and 0.10 oz/ton silver over 5.0 feet, extended mineralization about 150 feet to the east on the 243 Vein, close to the unconformity.
The Gwenivere program was designed to offset two historical surface reverse circulation (RC) intercepts. Initial drilling intersecting multiple structures had a significant assay interval of 1.35 oz/ton gold and 0.29 oz/ton silver over 3.5 feet. One hole was collared in Muck Bay 2 on the 5050 level and directed to the southeast. This hole intersected multiple dykes and transducers were installed to monitor the hydrology. Additional underground drilling in the Central Hollister, Gwenivere and West Gloria areas is planned to continue through the first quarter of 2019.
The Hatter Graben vein system provides the next leg of growth at Hollister. This vein system is located approximately 2,500 feet east of the Mine’s underground development and has been down dropped approximately 800 feet lower than the current Mine resource. The system of mineralized veins have a known vertical extent of 1,400 feet and strike length of 2,000 feet. This East-West trending zone is open along strike to the east and west and at depth and mineralization is strengthening in the East as historic high-grade intersections occur up to 4000 feet along strike to the east.
Gold and silver mineralization is dominantly in the Ordovician quartzites, siltites and argillites. Higher grades are associated with banded quartz veins from inches to feet in width and extensive zones of quartz vein stockwork and quartz matrix breccias also contain significant mineralization. Significant mineralized drillhole intercepts include 7.8 Au oz/ton over 1.4 feet, 1.77 AU oz/ton over 2.1 feet, 1.4 Au oz/ton over 2.3 feet, 0.54 Au oz/t over 7.8 feet, and 0.47 Au oz/ton over 12.5 feet.
In the third quarter of 2018, the first surface holes were in progress at Hatter Graben with the intent to extend the current resource to the east and west. Drill holes at 300-foot intervals have intersected swarms with multiple veins and mineralized breccias at the anticipated distance. Assays are pending.
The development of a decline to the Hatter Graben exploration target is under way with completion of the initial phased expected to be late in 2019.