Mining Intelligence and News
United States

Colosseum Project

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Categories

Summary

Mine TypeOpen Pit
Study CompletedPreliminary Economic Assessment
Study in ProgressFeasibility
StagePermitting
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
Mine Life... Lock
SnapshotThe Colosseum open pit mine is a past-producing mine, that was closed in 1993 due to a low gold price environment.

In 2021, Dateline Resources Ltd. committed to the first modern exploration and development program.

The October 2024 Scoping Study for the Colosseum Gold-REE project was conducted at a gold price of US$2,200 per ounce. An updated scoping study, dated May 23, 2025, has been prepared with a revised gold price forecast of US$2,900 per ounce. All other inputs remain unchanged.

Following the release of the Scoping Study, Dateline Resources has completed the Project Selection Stage and selected Nevada-based Kappes, Cassiday & Associates and Australian-based Australian Mine Design & Development (AMDAD) to manage the Bankable Feasibility Study.

On 8 April 2025, the US Department of the Interior confirmed Dateline’s right to continue operations under the existing Plan of Operations. The Rights include gold mining and rare earth elements (REE) exploration.
Latest NewsColosseum Gold Scoping Study Update: 208% Increase in Net Revenue and NPV of US$550 million     May 22, 2025

Owners

SourceSource
CompanyInterestOwnership
Dateline Resources Ltd. 100 % Indirect
Dateline Resources Ltd. owns 100% of the Colosseum Gold-REE Project.

Contractors

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Deposit type

  • Breccia pipe / Stockwork
  • Epithermal
  • Hydrothermal

Summary:

The Colosseum deposit style is a hydrothermal breccia pipe with a combination of epithermal mineralisation at original higher levels and mesothermal mineralisation at the lower levels.

The Colosseum deposit is located at the southern end of the Sevier foreland thrust belt in the southern Basin and Range Province, SW USA. The project lies within in the Clark Mountain Mining District in the northeast portion of the Clark Mountain Range. The district includes the Mountain Pass rare earth mine 10 kilometres south of the Colosseum Mine, numerous abandoned copper mines, and scattered fluorite, antimony, and tungsten prospects. Most gold and silver deposits in the district are within the northeast quadrant of the district north of Clark Mountain and are associated with emplacement of a felsic breccia complex into Precambrian basement rocks.

The deposit itself is associated with the emplacement of a breccia complex into Precambrian gneissic basement rocks. The complex is comprised of two felsite breccia pipes that form a northeast-southwest elongate zone, which contains mineralised zones of disseminated auriferous pyrite.

Gold at the Colosseum deposit is generally sub-microscopic and associated with sulphide mineralisation, chiefly pyrite. It occurs as free gold, with minor alloyed silver. Gold is primarily in contact with pyrite, in fractures in the pyrite or along pyrite grain edges. It also occurs as isolated particles in quartz and other gangue minerals but spatially always close to pyrite but rarely as particles encased in euhedral pyrite.

The gold mineralisation comprises disseminated auriferous pyrite hosted by a combination of felsite dyke intrusion, felsite breccias, sedimentary breccias and altered granite.

Mineralisation is diffuse and not hosted exclusively by a particular rock type.

There is no obvious visible lithological or structural control to the gold mineralisation, save for a broad NE/SW-striking enriched zone, presumably a structural corridor related to the felsite intrusions.

No geological interpretation per se for the mineralisation has been completed as the gold grades define the gold mineralisation in the various host rocks. Any wireframe for the gold mineralisation would ultimately be a simple grade shell.

Lithological units were delineated for the felsite/felsite breccia, sedimentary breccia and granite.

There is insufficient data to define with confidence any specific or significant fault structure playing a role in the control of mineralisation.

No oxidation surface was created due to a lack of logging data.

Dimensions
The Mineral Resources have an 800m by 800m surface extent. With two separate bodies 200x200m

The mineralisation is exposed at surface and the Mineral Resources continue to a depth of approximately 300m below surface at an RL of 1410m.

The lower limit to the Mineral Resource is an arbitrary one being the result of a supplied pit shell from a cursory pit optimisation study. The mineralisation is open at depth and laterally to the southeast, beyond the North Pit zone.

Reserves

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Mining Methods

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Required Heavy Mobile Equipment

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

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Commodity Production

CommodityUnitsAvg. AnnualLOM
Gold koz 71635
All production numbers are expressed as metal in doré.

Operational metrics

Metrics
Annual ore mining rate  ....  Subscribe
Annual milling capacity  ....  Subscribe
Annual processing rate  ....  Subscribe
Stripping ratio  ....  Subscribe
Waste tonnes, LOM  ....  Subscribe
Ore tonnes mined, LOM  ....  Subscribe
Total tonnes mined, LOM  ....  Subscribe
Tonnes processed, LOM  ....  Subscribe
* According to 2025 study.

Production Costs

CommodityUnitsAverage
All-in sustaining costs (AISC) Gold USD  ....  Subscribe
C1 cash costs Gold USD  ....  Subscribe
Assumed price Gold USD  ....  Subscribe
* According to 2025 study / presentation.

Project Costs

MetricsUnitsLOM Total
Pre-Production capital costs $M USD  ......  Subscribe
Sustaining CapEx $M USD  ......  Subscribe
Closure costs $M USD  ......  Subscribe
Total CapEx $M USD  ......  Subscribe
OP OpEx $M USD  ......  Subscribe
Processing OpEx $M USD 333
Total OpEx $M USD  ......  Subscribe
Gross revenue (LOM) $M USD  ......  Subscribe
Net revenue (LOM) $M USD  ......  Subscribe
$M USD  ......  Subscribe
Pre-tax IRR, %  ......  Subscribe
Pre-tax payback period, years  ......  Subscribe

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jun 27, 2025

Workforce

Aerial view:

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