Mexico

Ixtaca Project

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Overview

Mine TypeOpen Pit
StagePermitting
Commodities
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
Mine Life11 years (as of Jan 1, 2019)
ShapshotIn July 2022, the Ministry of Economy notified Almaden that its mineral titles are “ineffective” but that the title applications were filed in conformity with the Mexican mineral title law. The Company understands this to mean that the mineral title has reverted to application status, and that these applications preserve the mineral rights for Almaden but do not allow the Company to engage in exploration, until the court-ordered indigenous consultation is completed.

Almaden intends to interact with authorities in Mexico in order to clarify next steps and facilitate the government’s execution of its responsibilities. At present there is no timeline for consultation by the Ministry of the Economy with indigenous communities.

Owners

SourceSource
CompanyInterestOwnership
Almaden Minerals Ltd. 100 % Indirect
Compania Minera Gorrión S.A. de C.V. 100 % Direct
The Tuligtic Property is held 100 percent (%) by Compania Minera Gorrión S.A. de C.V. (Minera Gorrión), a wholly owned subsidiary of Almaden Minerals Ltd.

Contractors

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Deposit type

  • Epithermal
  • Vein / narrow vein

Summary:

The principal deposit-type of interest on the Tuligtic Property is low- to intermediate- sulphidation epithermal gold-silver mineralization. This style of mineralization is recognised at the Ixtaca Zone but property scale high level epithermal alteration suggests that mineralization of this type can exist elsewhere on the Project. The Tertiary bodies intruding the Tamaulipas Limestones and the tertiary volcanics, makes the Property also prospective for Porphyry copper-gold-molybdenum (Cu-Au-Mo) and peripheral Pb-Zn Skarn deposits.

Mineralization
Two styles of alteration and mineralization are identified in the area: (1) copper- molybdenum porphyry style alteration and mineralization hosted by diorite and quartz- diorite intrusions; (2) silver-gold lowsulphidation epithermal quartz-bladed calcite veins hosted by carbonate rocks and spatially associated with overlying volcanic hosted texturally destructive clay alteration and replacement silicification.

Outcropping porphyry-style alteration and mineralization is observed in the bottoms of several drainages where the altered intrusive complex is exposed in erosional windows beneath post mineral unconsolidated ash deposits. Multiple late and post mineral intrusive phases are identified crossing an early intensely altered and quartz-veined medium-grained feldspar phyric diorite named the Principal Porphyry. Other intrusive types include late and post mineral mafic dykes and an inter-mineral feldspar-quartz phyric diorite. Late mineral mafic dykes are fine grained and altered to chlorite with accessory pyrite. Calcsilicate (garnet-clinopyroxene) altered limestone occurs in proximity to the intrusive contacts and is crosscut by late quartz-pyrite veins. Early biotite alteration of the principal porphyry consists of biotiteorthoclase flooding of the groundmass. Quartz veins associated with early alteration have irregular boundaries and are interpreted to be representative of A-style porphyry veins. These are followed by molybdenite veins which are associated with the same wall rock alteration. Chalcopyrite appears late in the early alteration sequence. Late alteration is characterized by intense zones of muscovite-illite-pyrite overprinting earlier quartz-K-feldspar-pyrite ± chalcopyrite veining and replacing earlier hydrothermal orthoclase and biotite. Stockwork quartz-pyrite crosscuts the A-style veins and is associated with muscovite-illite alteration of biotite. The quartz-sericite alteration can be texturally destructive resulting in white friable quartz-veined and pyrite rich rock. Pyrite is observed replacing chalcopyrite and in some instances chalcopyrite remains only as inclusions within late stage pyrite grains.

The veining of Ixtaca epithermal system displays characteristics representative of intermediate and low sulphidation deposits. These include typical mill feed and gangue mineralogy (electrum, sphalerite, galena, adularia, and carbonates), mineralization dominantly in open space veins (colloform banding, cavity filling).

To date two main vein orientations have been identified in the Ixtaca deposit:
• 060 trending sheeted veins hosted by limestone;
• 330 trending veins hosted by shale;

The Main Ixtaca and Ixtaca North vein swarms are spatially associated with two altered and mineralised sub parallel ENE (060 degrees) trending, sub-vertical to steeply north dipping dyke zones. The Main Ixtaca dyke zone is approximately 100m wide and consists of a series of 2m to over 20m true width dykes. The Ixtaca North dyke zone is narrower and comprises a steeply north-dipping zone of two or three discrete dykes ranging from 5 to 20m in width.

Individual veins and veinlets within the Main Ixtaca and Ixtaca North vein swarm zones cannot be separately modelled. Wireframes were created that constrain the higher grade, more densely veined areas, however as the vein swarms are anastomosing and sheeted in nature, therefore these wireframes include significant barren limestone material enclosed by veins within the vein swarm (See Figure 7-10).

The Main and North zones have been defined over 650m and tested over 1000m strike length with highgrade mineralization intersected to depths up to 350m vertically from surface. In 2016 Almaden conducted a drill program to test for additional veins to the north of the Ixtaca North Zone. This program resulted in better definition of the Ixtaca North zone and was successfully demonstrated that limestone mineralization remains open to the north and at depth.

The Chemalaco Zone dips moderately-steeply at approximately 22 degrees to the WSW. The strike length of the Chemalaco Zone has been extended to 450m with high-grade mineralization intersected to a vertical depth of 550m, or approximately 700m down-dip. An additional sub-parallel zone has been defined underneath the Chemalaco Zone dipping 25 to 50 degrees to the WSW, intersected to a vertical depth of 250m, approximately 400m down-dip over a 250m strike length. The Chemalaco zone remains open to depth and along strike to the northwest. Additional parallel veins further to the east have been identified in core and the zone is remains open in this direction as well. In the Chemalaco zone, assays indicate that, while mineralisation appears similar in core, higher silver grades occur in the upper portion of the drilled area and higher gold grades occur at depth.

The Main Ixtaca, Ixtaca North and Chemalaco vein zones are largely concealed by overlying altered volcanic rocks although the limestone and Main Ixtaca zone of veining does crop out on the west side of Cerro Caolin, the hill under which the Main Ixtaca Zone occurs. The volcanics above the Main Ixtaca Zone are intensely clay altered and locally silicified but barren of significant gold and silver at surface. The Cerro Caolin volcanic hosted clay alteration zone extends to the SE roughly one kilometer and represents a significant drill target.

Studies of mineral assemblages in hand specimen, transmitted and reflected light microscopy and SEM analyses have been carried out in order to construct a paragenetic sequence of mineral formation. This work completed by Herrington (2011) and Staffurth (2012) reveals that veining occurs in three main stages. The first stage is barren calcite veining. This is followed by buff brown and pink colloform carbonate and silicate veins containing abundant silver minerals and lower gold. The third stage of veining contains both gold and silver mineralization. The dominant gold-bearing mineral is electrum, with varying Au:Ag ratios. The majority of grains contain 40-60wt (weight) % gold but a few have down to 20wt% (Staffurth, 2012). Gold content occasionally varies within electrum grains, and some larger grains seem to be composed of aggregates of several smaller grains of differing composition (Staffurth, 2012). Electrum often appears to have been deposited with late galena-clausthalite both of which are found as inclusions or in fractures in pyrite. It is also closely associated with silver minerals as well as sphalerite and alabandite. Gold is also present in uytenbogaardtite (Ag3AuS2). This mineral is associated with electrum, chalcopyrite, galena, alabandite, silver minerals, and quartz in stage three mineralization (Herrington, 2011; Staffurth, 2012). Apart from electrum, the dominant silver bearing minerals are polybasite (-pearceite) and argentian tetrahedrite plus minor acanthite-naumannite, pyrargyrite and stephanite. They are associated with sulphides or are isolated in gangue minerals (Staffurth, 2012).

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

CommodityUnitsAvg. AnnualLOM
Gold koz 91946
Silver koz 6,14063,372
Gold Equivalent oz 173,000
Silver Equivalent koz 12,900
All production numbers are expressed as metal in doré.

Operational metrics

Metrics
Daily ore mining rate 00000
Daily milling rate 00000
Stripping / waste ratio 000
Waste tonnes, LOM 000
Ore tonnes mined, LOM 000
Tonnes processed, LOM 00
* According to 2019 study.

Production Costs

CommodityUnitsAverage
Cash costs Silver Equivalent USD 9.55 / oz *  
Cash costs Gold Equivalent USD 716 / oz *  
All-in sustaining costs (AISC) Silver Equivalent USD 11.3 / oz *  
All-in sustaining costs (AISC) Gold Equivalent USD 850 / oz *  
Assumed price Silver USD 17 / oz *  
Assumed price Gold USD 1,275 / oz *  
* According to 2019 study / presentation.

Operating Costs

Currency2019
OP mining costs ($/t milled) USD 15.2 *  
Processing costs ($/t milled) USD  ....  Subscribe
G&A ($/t milled) USD  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe
* According to 2019 study.

Project Costs

MetricsUnitsLOM Total
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Sustaining CapEx $M USD  ......  Subscribe
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OP OpEx $M USD  ......  Subscribe
Processing OpEx $M USD 504
G&A costs $M USD 52
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Heavy Mobile Equipment

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Personnel

Mine Management

Source Source
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