Overview
Status | Inactive / Suspended |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Cut & Fill
- Longhole stoping
- Cemented backfill
|
Production Start | ...  |
Midas mine was acquired by Hecla Mining in July 2018. Mine's production and financial results have been included into the Nevada Operations Segment since then.
Production at the Midas mine was suspended in late 2019. |
Source:
p. 147
Klondex Midas Operations Inc. is an indirect subsidiary of the Hecla Mining Company.
Contractors
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Deposit Type
- Vein / narrow vein
- Epithermal
Summary:
On a general scale, the hydrothermal system and subsequent mineralization developed at Midas is currently interpreted as a low sulfidation, epithermal precious-metal vein system, as part of a larger magmatic system at depth.
The Midas Mine is the largest known Au-Ag epithermal deposit along the Northern Nevada Rift (“NNR”) and is located, located in the mining district of Midas, also known as the Gold Circle district.
The Midas deposit consists of a series of complex steeply dipping, quartz-calcite-adularia precious metal veins hosted by volcanic and volcanoclastic rocks and locally contains mineral grades greater than (>) ten ounces per ton (opt) of gold. Gold mineralization occurs as electrum and is intimately associated with selenide and sulfide minerals. It belongs to a suite of middle Miocene low-sulfidation epithermal gold and silver mineralizing systems associated with magmatism and faulting along the NNR (Leavitt et al., 2004). The mineralization model at Midas is a shallow, low-sulfidation, vertically- and laterally-zoned, epithermal gold-silver system. Rocks in the Midas district are primarily ash flow, air-fall and lithic tuffs, felsic plugs, volcanoclastic sediments and gabbroic sills and dikes.
Gold and silver mineralization at Midas is hosted in several north-west striking veins. The veins are divided into four principle groups based on their location and orientation. The two groups hosting mineral resources are the Main Veins ........

Mining Methods
- Cut & Fill
- Longhole stoping
- Cemented backfill
Summary:
Longitudinal sublevel (longhole) stoping has historically been the primary mining method for the five narrow Main Veins at Midas as well as the East Veins, including 905, 9052, and 805. From the portal, there are three major haulages that access these veins through eight different spirals. Generally, upper and lower sections of the same spiral connect only through ventilation/escape raises. All mineralized material produced is hauled out of the portal in trucks to a temporary stockpile where it is loaded onto a surface haul truck and delivered to the on-site mill.
Mine development is controlled by geological conditions in the area. For the sublevel stoping method, sill development is driven at a nominal seven feet wide by twelve feet high to accommodate the size of longhole drills and two-cubic yard (yd3) loaders. Where the vein thickness is wider than six feet, the sill width is increased to capture the entire vein. Sills are typically driven 600 feet north and south from the spiral cross cut. Once sills are developed, stoping begins. Stopes are drilled with a longhole drill from the floor of one level to the back of the one below, then remote mucked from the bottom level, and finally backfilled from the top level.
Typically, the mineralized material is divided into stope blocks of about four levels for development, or 200 feet vertically. Stoping begins by creating a cemented backfill barrier pillar at the bottom level of the mineralized material bloc ........

Source:

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Flow Sheet:
Summary:

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Production:
Commodity | Units | 2017 | 2016 | 2015 | 2014 |
Gold
|
oz
| 34,343 | 29,824 | 28,838 | 19,058 |
Silver
|
oz
| ......  | ......  | ......  | ......  |
Gold Equivalent
|
oz
| ......  | ......  | ......  | ......  |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | 2018 | 2017 | 2016 | 2015 | 2014 |
Daily milling capacity
| 1,200 tons | 1,200 tons | 1,200 tons | 1,200 tons | |
Ore tonnes mined
| | 156,927 tons | 193,856 tons | 175,173 tons | |
Tonnes milled
| | 157,363 tons | 190,982 tons | 174,714 tons | 116,889 tons |
Daily milling rate
| | | 523 tons | 479 tons | 320 tons |
Reserves at December 31, 2022:
Midas mineral resources are reported at a gold equivalent cut-off grade of 0.237 oz/ton. Metallurgical recoveries: 90% for gold and 70% for silver. A gold-equivalent cut-off grade of 0.1 oz/ton and a gold price of $1700/oz used for Sinter Zone with resources undiluted.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured
|
2 k tons
|
Gold
|
0.68 oz/ton
|
1 koz
|
Measured
|
2 k tons
|
Silver
|
7.6 oz/ton
|
14 koz
|
Indicated
|
76 k tons
|
Gold
|
0.42 oz/ton
|
32 koz
|
Indicated
|
76 k tons
|
Silver
|
5.7 oz/ton
|
430 koz
|
Measured & Indicated
|
78 k tons
|
Gold
|
0.43 oz/ton
|
33 koz
|
Measured & Indicated
|
78 k tons
|
Silver
|
5.7 oz/ton
|
444 koz
|
Inferred
|
1,232 k tons
|
Gold
|
0.5 oz/ton
|
615 koz
|
Inferred
|
1,232 k tons
|
Silver
|
6.3 oz/ton
|
7,723 koz
|
Commodity Production Costs:
| Commodity | Units | 2017 | 2016 |
Cash costs (sold)
|
Gold Equivalent
|
USD
|
1,008 / oz
|
981 / oz
|
Cash costs (sold)
|
Gold
|
USD
|
|
|
† Net of By-Product.
Operating Costs:
| Units | 2016 |
UG mining costs ($/ton mined)
|
USD
| 221 |
Financials:
| Units | 2017 | 2016 |
Capital expenditures
|
M USD
|
16.3
|
23.8
|
Revenue
|
M USD
|
59.6
|
63.8
|
Operating Income
|
M USD
|
-8.8
|
-5.1
|
Corporate Filings & Presentations:
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