Mining Intelligence and News
United States

Mount Hamilton Project

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Mine TypeOpen Pit
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
Mine Life... Lock


Bendito Resources Inc. 100 % Indirect
On May 1, 2024, Bendito Resources Inc. closed on the previously announced transaction to acquire 100% of Mt Hamilton LLC, the owner of the Mt. Hamilton gold and silver project.

Deposit type

  • Skarn
  • Epithermal


Mineralization at Mt. Hamilton consists of skarn hosted tungsten, molybdenum, and copper +/- zinc with later epithermal gold and silver. Gold mineralization is primarily hosted in a 200 to 300 ft thick skarn horizon, bounded by upper (200 ft thick) and lower (450 ft thick) hornfels units. The bounding hornfels had lower permeability and were therefore less receptive to late-stage mineralization. The interbedded skarn in the Centennial area was subject to late-stage, low-angle faulting. These faults were conduits to late mineralizing solutions and oxidation. The result is an oxide-hosted epithermal gold deposit overprinting a retrograde polymetallic skarn. The main Centennial precious metal mineralization is contained within a southeast dipping (15° to 20°) tabular zone that ranges from 20 to 250 ft in thickness. In the NE Seligman area, ore grade mineralization appears to be largely stratiform in shallow-dipping, bedding-parallel, structurally and chemically prepared zones with local high-angle, cross-cutting, possible "feeder" zones (Burgoyne, 1993). At Centennial, the mineralization is controlled by late low-angle structures that are discordant to bedding and oxidized to significant depth. Gold grades of samples within the retrograde alteration range from <0.001 oz/t Au (lower analytical method detection limit) to 0.995 oz/t. The occasional high grades appear to be associated with crosscutting structures and veins within the skarn as described below.

In the Centennial deposit, weathering and oxidation of original sulfide mineralization caused formation of oxide mineralization (with low sulfide mineral residuals) from which gold is recoverable by cyanide heap leaching. In general, the acid generating capacity of the surrounding carbonate rocks is low or nil, and their acid consuming capacity is high. Gold is present as free gold, residing in iron oxide minerals or quartz, and adsorbed on clay minerals. Sulfosalt-bearing veins may be associated locally with the higher grades of gold and particularly silver. These veins cut both skarn and intrusive rocks and are closely associated with zones of retrograde alteration. These veins range in thickness from about 2 to 60 cm. In the Seligman deposit the mineralization is similar to Centennial but is, on average, thinner. Widely spaced drilling between the two deposits indicates that they represent one contiguous mineralized system that could be connected by additional drilling. Locally, more sulfide minerals are preserved at Seligman in comparison to Centennial. As seen in the mine excavations of the NE Seligman deposit, veins seem to exhibit strong continuity along strike.



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Mining Methods


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Crushers and Mills

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CommodityUnitsAvg. AnnualLOM
Gold koz 69416
Silver koz 2791,743
Gold Equivalent oz 73,000
All production numbers are expressed as metal in doré.

Production Costs

Cash costs Gold Equivalent USD 558 / oz *  USD
Assumed price Silver USD 20 / oz *  USD
Assumed price Gold USD 1,300 / oz *  USD
* According to 2014 study / presentation.

Operating Costs

OP mining costs ($/t mined) USD 1.66 *  USD
OP mining costs ($/t milled) USD  ....  Subscribe
Processing costs ($/t milled) USD  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe
* According to 2014 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
OP OpEx  ......  Subscribe
Processing OpEx $M USD 92.4
Refining and transportation $M USD  ......  Subscribe
G&A costs $M USD 18.9
Total OpEx $M USD  ......  Subscribe
Mining Taxes $M USD  ......  Subscribe
Income Taxes $M USD  ......  Subscribe
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Gross revenue (LOM) $M USD  ......  Subscribe
Net revenue (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 @ 8% $M USD  ......  Subscribe
After-tax NPV @ 5% $M USD  ......  Subscribe
After-tax NPV @ 8% $M USD  ......  Subscribe
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