Mining Intelligence and News
United States

Copperstone Mine

Click for more information



Mine TypeUnderground
  • Gold
Mining Method
  • Mechanized Cut & Fill
Backfill type ... Lock
Mine Life... Lock
SnapshotWithin the Copperstone Project is the Copperstone Mine. Existing infrastructure includes a power line, substation, three water wells, 4,300ft of underground development, supporting infrastructure, offices, maintenance shops, a laboratory building, permitted tailings facility, 600 ton per day ball mill, all sufficient, with modest refurbishment, for the currently contemplated restart of operations at the Copperstone Mine.

Copperstone Project Development
Further updates to the mine design commenced in Q1 2023 and a Preliminary Economic Assessment (PEA) was released in June 2023. Sabre Gold management worked with Hard Rock Consulting, LLC to complete the PEA, which included comprehensive reviews of the construction, operations and costs, to provide confidence for potential project commencement and completion within budget and schedule. Trade off studies on initial capital items and initial earthworks will commence as soon as the Company moves towards a formal construction decision.


Sabre Gold Mines Corp. 100 % Indirect



- subscription is required.

Deposit type

  • Vein / narrow vein
  • Volcanic hosted
  • Epithermal


The Copperstone deposit is a mid-Tertiary, detachment fault related gold deposit. Mineralization is predominantly controlled by the northwest trending shallow angle Copperstone fault and shear zone. These structures are not confined to any lithologic unit, although the majority of the mineralization is hosted in quartz latite porphyry. Breccia textures as well as chloritization, silicification, and hematite and specularite flooding are reliable indications of gold mineralization.

The Copperstone deposit is presently best described as a mid-Tertiary, detachment-fault related gold deposit. Detachment faults are low-angle (up to 30°) normal faults of regional extent that have accommodated significant regional extension by upward movement of the foot-wall (lower-plate) producing horizontal displacements on the order of tens of kilometers. Common features of these faults are supracrustal rocks in the upper-plate on top of lower-plate rocks that were once at middle and lower crustal depths, mylonitization in lower plate rocks that are cut by the brittle detachment fault, and listric and planar normal faults bounding half-graben basins in the upper plate (Davis and Lister, 1988).

Salem (1993) suggests that the Copperstone deposit might be further classified as a new sub-set of volcanic-hosted epithermal precious-metal deposits, postulating that Copperstone was created during a late stage of detachment faulting, and that localization of gold deposition was controlled by boiling. Gold deposition was, according to Mahmoud’s well-presented interpretation, related to the circulation of brine fluids driven by hot mid-Tertiary granitic lower plate rocks that may have also contributed water and or metals, causing ascending brines to move along the N- to NE- dipping Moon Mountain detachment fault at the Copper Peak area to the south. The fluids continued to ascend along the Copperstone listric fault and a series of high angle NE and NW faults that crosscut the Copperstone listric fault. This structure acted as conduit that was kept open by ongoing faulting without deposition until the fluids reached the boiling stage, perhaps as a result of decompression. The boiling fluid mixed with another less saline fluid within the ore horizon, a mixing that led to the precipitation of gold mainly along the brecciated hanging wall and footwall of the Copperstone listric fault, as open space-fillings and replacement mineralization (Salem, 1993).

Gold mineralization at Copperstone occurs in the hanging wall of the Moon Mountain detachment fault, which has not been penetrated in drilling to date. Gold mineralization is largely restricted to the immediate vicinity of the Copperstone fault (also referred to as the Copperstone shear or the Copperstone structure), a moderately northeast-dipping, semi-planar zone of shear which is interpreted as a listric splay of the Moon Mountain detachment, and which has hosted the bulk of the gold historically produced from the Copperstone mine. The Copperstone fault strikes about N30° to 60°W and dips from 20° to 50° to the northeast. The associated brecciated fault zone ranges from 45 ft to 180 ft in width with characteristic fault gouge, multiphase breccia textures, shear fabric, and intense fracture sets across this width (MDA, 2000).

The Copperstone fault appears to be a brittle deformation feature situated within the extremely deformed upper plate volcanic sequence. The fault presents strong evidence of shearing, with schistose textures and conjugate sets of planar and curved faults indicated by fault gouge. Brecciation is observable in the open pit, as are steeply northeast dipping, northwest-striking fractures and narrow shear zones. Mineralization is known to occur in association with both the primary Copperstone listric fault as well as high-angle, secondary fault structures. All mineralization appears to be cut off at the southeastern edge of the pit by a northeast striking fault that dips to the southeast. Most of the fractures in the volcanic sequence are highly irregular and discontinuous, but the Copperstone structure has remained a dependable target for exploration and mining.

Mineralization in the A, B, and C zones occurs along the primary Copperstone fault as well secondary structures within the zone of shear. Underground mapping has shown a number of steeper northwesttrending faults and fractures that localize alteration and mineralization in and around quartz-Fe oxide+/-Cu oxide veins. Observations show that where such high-angle structures intersect the low-angle (Copperstone fault) structures, a favorable site is prepared. Where the Copperstone listric fault is disrupted, a dilatant zone may occur, resulting in higher grade and thickness of the gold mineralization.

The D zone contains large imbricate slices of interbedded limestone and sandstone, of which the limestones have been largely replaced by specularite, earthy hematite and silica. In many drillholes, silica-magnetite-specularite-chlorite replacement bodies occur in two limestone layers of variable thickness, but generally no more than 5-10 ft. In some locations iron oxides form a matrix in silicified limestone but nearby there may be evidence for direct replacement of limestone by iron oxides. It is possible that some of the silicified limestone is actually a pure white quartzite that has been brecciated. This would mean that silicification does not precede iron-oxide introduction.



- subscription is required.

Mining Methods


- subscription is required.


Crushers and Mills


- subscription is required.



- subscription is required.


CommodityUnitsAvg. AnnualLOM
Gold oz 38,000166,172
All production numbers are expressed as metal in doré.

Operational metrics

Daily ore mining rate 600 tons *
Daily processing rate 840 tons *
Waste tonnes, LOM 537,001 tons *
Ore tonnes mined, LOM 884,106 tons *
Total tonnes mined, LOM 1,421,107 tons *
Tonnes processed, LOM 884,106 tons *
* According to 2018 study.

Production Costs

Cash costs (sold) Gold USD 684.03 / oz *  
Total cash costs (sold) Gold USD 713.94 / oz *  
All-in sustaining costs (sold) Gold USD 874.83 / oz *  
Assumed price Gold USD 1,250 / oz *  
* According to 2018 study / presentation.

Operating Costs

UG mining costs ($/t milled) USD 69.4 *  
Processing costs ($/t milled) USD  ....  Subscribe
G&A ($/t milled) USD  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe
* According to 2018 study.

Project Costs

MetricsUnitsLOM Total
Initial CapEx $M USD  ......  Subscribe
Sustaining CapEx $M USD  ......  Subscribe
Closure costs $M USD  ......  Subscribe
Total CapEx $M USD  ......  Subscribe
UG OpEx $M USD  ......  Subscribe
Processing OpEx $M USD 32.1
Refining and transportation $M USD  ......  Subscribe
G&A costs $M USD 12.1
Total OpEx $M USD  ......  Subscribe
Mining Taxes $M USD  ......  Subscribe
Income Taxes $M USD  ......  Subscribe
Royalty payments $M USD  ......  Subscribe
Gross revenue (LOM) $M USD  ......  Subscribe
Net revenue (LOM) $M USD  ......  Subscribe
EBITDA (LOM) $M USD  ......  Subscribe
Pre-tax Cash Flow (LOM) $M USD  ......  Subscribe
After-tax Cash Flow (LOM) $M USD  ......  Subscribe
Pre-tax NPV @ 5% $M USD  ......  Subscribe
Pre-tax NPV @ 10% $M USD  ......  Subscribe
Pre-tax NPV @ 7.5% $M USD  ......  Subscribe
After-tax NPV @ 5% $M USD  ......  Subscribe
After-tax NPV @ 10% $M USD  ......  Subscribe
After-tax NPV @ 7.5% $M USD  ......  Subscribe
Pre-tax IRR, %  ......  Subscribe
After-tax IRR, %  ......  Subscribe
Pre-tax payback period, years  ......  Subscribe
After-tax payback period, years  ......  Subscribe

Required Heavy Mobile Equipment


- subscription is required.


Mine Management

Job TitleNamePhoneProfileRef. Date
....................... Subscription required ....................... Subscription required ........... Subscription required Subscription required Dec 19, 2023
....................... Subscription required ....................... Subscription required Subscription required Dec 19, 2023

Total WorkforceYear
...... Subscription required 2018

Aerial view:


- subscription is required.