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Mexico

San Agustin Mine

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Overview

Mine TypeOpen Pit
StageResidual leach
Commodities
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
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SnapshotThe San Agustin mine is an open-pit, heap leach, gold-silver operation located 11 km from the El Castillo mine. Together, they make up the El Castillo Complex.

In Aug 2023, the Argonaut (previous owner) signed an agreement to acquire the necessary land to complete mining of the current reserve base at the San Agustin mine. Subject to receipt of the necessary permit, expected in the first half of 2024, mining is expected to continue during 2025.

November 14, 2024, the San Agustin Mine recently ceased mining activities due to permit constraints and is producing gold from existing leach pads. Heliostar has submitted a permit application to expand the open pit that would allow mining at San Agustin to recommence in 2025. Without approval, the San Agustin Mine will transition to care and maintenance upon completion of leaching operations.

Owners

SourceSource
CompanyInterestOwnership
Minera Real del Oro S.A. de C.V. (operator) 100 % Direct
Heliostar Metals Limited 100 % Indirect
July 15, 2024 - Florida Canyon Gold Inc. is a newly listed company formed pursuant to the spin-out of the United States and Mexican operations of Argonaut Gold Inc., including the Florida Canyon mine in Nevada, U.S.A. and the San Agustin mine, La Colorada mine, San Agustin mine, El Castillo mine, and Cerro del Gallo project in Mexico.

Florida Canyon Gold Inc. owned the El Castillo complex through Minera Real del Oro, S.A. de C.V., which owns and operates the complex.

On November 8, 2024, Heliostar Metals Ltd. announced completion of the acquisition of a 100% interest in all of Florida Canyon Gold Inc.’s mining assets in Mexico for cash consideration of US$5,000. The assets include the San Agustin mine (formerly the El Castillo Complex), La Colorada mine, Cerro del Gallo project, and San Antonio project.

Pursuant to the Transaction, Heliostar acquired those Florida Canyon Gold subsidiaries which collectively own 100% of the following properties.

Contractors

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Deposit type

  • Epithermal
  • Vein / narrow vein
  • Porphyry

Summary:

The San Agustin Project is located in Northwest Mexico in the east flank of the Sierra Madre Occidental (SMO) bordering the great Mesa Central Mexicana. The oldest rocks in the region are mica schists and mylonites. These are overlain by an Upper Jurassic to Lower Cretaceous sedimentary flysch sequence mainly composed of an alternating sequence of shale and fine-grained sandstone with occasional horizons of calcareous shale and thin layers of limestone.

The volcanic complex of the SMO is present in the area. The Lower Volcanic Complex occurs as agglomerates, tuffs, and andesitic flows. The Upper Volcanic Complex consists of a sequence of rhyolite tuffs, crystal tuffs, and ash tuffs. Discordantly covering all previously mentioned lithological units is a package of welded rhyolite tuffs. The most recent igneous unit observed is composed of Pleistocene vesicular basalt flows that cover some of the valleys to the southeast of the Project.

There is a widespread occurrence of a poorly consolidated conglomerate that fills wide valleys associated with basin-and-range extensional normal faulting. A quartz monzonite stock, a biotite-rich volcanic rhyolite dome, and a package of ash and crystal tuffs also occur in the region.

Two main structural trends were identified in the San Agustin area. Although Mineralization at the Project appears to be related to or associated with the northeast-trending structures, geophysical data shows anomalies aligned with the northwest-trending faults and fractures.

The most obvious structure recognized on the Project is the Main Fault, which trends northwesterly and dips steeply to the southwest.

The area of known mineralization at the San Agustin Project is dominated by an igneous, quartz monzonite dome complex intruding a clastic sedimentary sequence composed of shale, mudstone, and less abundant sandstone. Both the intrusive complex and the sedimentary sequence occur on a dominant northwest trend with sub-vertical dips. Mineralization is emplaced through a strong and widespread system of sulphide rich veins, veinlets and fissure fillings that make the system similar to a disseminated deposit. Locally, mineralization can be observed following lithological controls in the sedimentary rocks, especially where they run parallel to sediment-intrusive contacts. The most dominant alteration type is phyllic, characterized as an assemblage of sericite-quartz-pyrite mineralization.

Mineralization
The host rocks for mineralization at San Agustin are quartz monzonite-dacite bodies and the sedimentary sequence they intrude. Mineralization is emplaced through a strong and widespread system of sulphide rich veins, veinlets, and fissure fillings that make the system similar to a disseminated deposit. Fracture systems follow two main project-scale trends that run northeast and northwest. Locally, mineralization can be observed following lithological controls in the sedimentary rocks, especially where they run parallel to sediment-intrusive rock contacts. Mineralization is also observed in the flow facies of the intrusion and is usually characterized by disseminated pyrite and in parallel veinlets. A component of the pyrite is thought to be pre-mineralization and associated with early phyllic alteration. The mineral system has very little silica and is more related to sulphide fracture filling. Epithermal boiling textures were observed locally such as bladed textures, coliform silica, or drusy quartz. These epithermal textures are not common. Some structures with cryptocrystalline jasperoid have also been found in deeper drill intercepts within sulphide zones. Two late phases of mineralization were identified with one carrying sphalerite and pyrite, and the other, galena and sphalerite. This mineralization is related to an epithermal low sulphidation system superimposed over the intrusion-related gold system.

The Main Fault, an important northwest striking and westerly dipping post-mineral fault, bisects the mineralized area showing differences in mineralization on either side. On the hanging-wall (west side) it is common to find structures rich in manganese and barite that are not observed in the footwall. The hanging-wall block also has higher silver and lead grades than the footwall block.

The sulphide boundary is located within a range of 30 m to 170 m below the surface with an average depth of about 65 m. The boundary is reached when the rock colour turns grey and disseminated pyrite becomes visible. The transition zone is commonly less than 1 m wide. The boundary’s surface is undulating and erratic across the deposit, due to the many faults and fractures controlling ground water in the area.

Alteration
The predominant alteration type is phyllic alteration characterized as an assemblage of sericite-quartzpyrite mineralization. In some areas it appears that the host rock was pervasively altered, destroying the original texture and converting biotite and feldspars to sericite. The matrix also shows the presence of sericite, silicification, and disseminated pyrite. In some areas veinlets of jarosite and alunite are observed and thought to be products associated with acid leaching of pyrite as opposed to hydrothermal alteration.

A phase of early potassic alteration was observed but is less common. These zones are characterized by the presence of moderate to pervasive secondary biotite associated with veinlets of quartz-magnetite and disseminated magnetite. Phyllic alteration is superimposed on this early potassic alteration with the latter being closely associated with mineralization.

In the areas more distal to mineralization, the intrusion is typically phaneritic with a coarse porphyritic texture with only propylitic alteration shown by moderate chlorite replacement of ferromagnesian minerals.

Deposit Descriptions
The San Agustin deposit is roughly 1,500 m long by 800 m wide. The average depth of oxide material is 65-100 m below surface. Gold mineralization is found along faults and fractures within the host igneous and sedimentary rocks and as disseminations in halos across the deposit. Sulphide mineralization extends, where drilled, down to an average depth of about 200 m with the deepest tested areas extending to 400 m below surface.

Mineral Deposit Type
The San Agustin Project does not fit entirely into an epithermal classification. The San Agustin deposit appears genetically and spatially related to onzonite stock with intense phyllic alteration and local tourmaline breccias. These factors may point towards a telescoped system associated with a deeper porphyry centre. This is supported by broad zones of potassic alteration that are overlapped by pervasive phyllic alteration; however, locally on the surface and in some drill holes, boiling textures, suggestive of an epithermal system do occur. Mineralization is mainly associated with pyrite that fills fractures, is disseminated, and occurs in the matrix of hydrothermal breccias. These form an extensive system of sulphide stockworks and disseminated mineralization dominated by pyrite.

Petrographic studies report intense phyllic alteration and the presence of two-phase inclusions that evidence boiling (Pérez-Segura, 2014).

The San Agustin deposit is interpreted to be a porphyry-style gold system related to Eocene aged intrusions emplaced into Cretaceous clastic and carbonate sedimentary rocks in an extensional tectonic setting. Gold mineralization occurs throughout the magmatic-hydrothermal system in space and time and is spatially related to early potassic development and an overprint of phyllic alteration. Supergene alteration, formed as a product of acid leaching, resulted in argillic-quartz alteration assemblages within the oxide zone of the deposit. The main gold event is associated with magmatic hydrothermal fluids corresponding to phyllic alteration.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnits20242023202220212020201920182017
Gold Equivalent oz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe64,768 68,815 10,946 
Gold oz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe61,84265,32310,302
Silver oz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe219,463244,47045,100
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.

Operational metrics

Metrics20242023202220212020201920182017
Stripping / waste ratio  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe0.73 0.44 0.43
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe8,453 kt7,379 kt939 kt
Waste  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe6,166 kt3,216 kt404 kt
Total tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe14,619 kt10,595 kt1,343 kt
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe8,291 kt7,408 kt1,004 kt
Daily processing rate  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
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^ Guidance / Forecast.

Production Costs

CommodityUnits20242023202220212020201920182017
Cash costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 863 / oz **   545 / oz **   385 / oz **  
All-in sustaining costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
^ Guidance / Forecast.
** Net of By-Product.

Operating Costs

Currency20232022
OP mining costs ($/t milled) USD  ....  Subscribe  ....  Subscribe
Crushing costs ($/t milled) USD  ....  Subscribe  ....  Subscribe
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G&A ($/t milled) USD  ....  Subscribe  ....  Subscribe

Financials

Units20242023202220212020201920182017
Capital expenditures (planned) M USD  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 13.9   7.5   27.8  
Sustaining costs M USD  ....  Subscribe  ....  Subscribe

Heavy Mobile Equipment

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Personnel

Mine Management

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EmployeesContractorsTotal WorkforceYear
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Aerial view:

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