Tropico: Located in the Fresnillo District - World's Largest Silver Mining Camp 

  • Summary 

    In March 2023 Radius Gold announced the discovery and acquisition of the Tropico, a new gold mineralized “hotspring type” sinter and breccia target within the world’s largest silver (plus gold) mining camp, the Fresnillo mining district in Zacatecas, Mexico. Radius has entered into an option agreement with local claim owners to acquire 100% of the property1. Radius will move quickly to acquire drill permits, conduct deep penetrating resistivity surveys to define pipe shape and commence drilling.

    The Tropico target is not yet drill tested and has every indication for the potential to make a great gold discovery:

    • Tropico is located in same host rocks as the major mines of the Fresnillio mining district – one of the world’s largest epithermal systems with estimated production to date of +3 billion ounces of silver plus gold, copper, lead, and zinc
    • The district has over 150 veins, mantos and chimney deposits including over 30 large scale ore producers and continues to produce new discoveries1
    • In 2005 MAG silver and Fresnillo Plc discovered Juanicipio with the Bonanza zone containing indicated resources 8Mt at 550g/t Ag, 1.95 g/t Au & 4.6% Zn+Pb*, entered into production in 2021, and is one of the world’s highest grade and largest primary silver (plus gold) development projects2
    • Tropico is a gold bearing breccia pipe, rimed by sinter and is highway accessible:
      • Assays in 2023 included significant gold values in rock chip samples from a sinter system.1
      • Sinter is typically very low grade or barren in precious metal content but can be the surface indication of a mineralized system at depth.  
      • Famous examples of epithermal gold and silver mines located below sinter deposits, both within the Fresnillo district and globally (e.g. Waihi - New Zealand, Lihir - PNG, McLaughlin - USA). 1

    Tropico Location

    The Tropico Target is located 30 km northwest of Fresnillo city, Zacatecas, Mexico (see Figure 1 "Tropico location"). The Tropico property is located 1 km off the paved national highway route 45 between Fresnillo and Durango. The ground is flat and has easy access to all areas via farm tracks. A pre-existing lease agreement that allows for exploration has been signed with the local community. 

    Target Model 

    Chimney bodies at Fresnillo are often cylindrical shaped brecciated pipes that crosscut the cretaceous volcano sedimentary host units and predate or are contemporaneous with silver, gold and base metal veins. The vein systems at Fresnillo are most frequently "blind", meaning they do not outcrop, and the tops of the orebodies are concealed to a depth of approximately 150m and deeper. Surface expressions can include geochemical path finder halo's, thin discontinuous quartz carbonate veinlets, and low temperature chalcedonic silica and sinter (Figure 2).

    Sinter is a formation of opaline silica deposited in a hotspring environment at surface. Sinter typically has a very low grade or barren precious metal content but can be the surface indication of a mineraliezed system at depth. There are many famous examples of epithermal gold and silver mines located below sinter deposits, both within the Fresnillo district and globally (e.g Waihi New ZealandPNG, McLaughlin  USA). See Figure 3 "Breccia Pipe & Sinter Target".


    Geology and Geochemistry 

    Outcrop within the Tropico property is sparse. From limited outcrop and float Radius geologists have identified an elliptical zone of intensely silicle hydrothermal breccias approximately 450 m x 250 m. Several of the outcrops and float blocks are composed of chalcedonic and opaline sinter. The Tropico breccias is hosted within finely bedded siltstones and dirty limestones, interpreted to be part of the Proaño group which hosts the major Fresnillo deposits. There are known active hot-spring and mercury occurrences nearby.1

    Radius collected and assayed 28 rock chip samples from the area of the silica breccia and sinter. Gold values ranged from 0.02 ppm to 0.88 ppm Au, with an average of 0.28 ppm Au, which is considered significant for a sinter system. In actual sinter material, the highest grade was 0.39 ppm Au. Mercury values are very high, with several samples exceeding >100 ppm Hg (the upper limit of detection). Typical epithermal path finder elements were also highly anomalous with Sb between 64 and 1135 ppm, As between 8 to 854 ppm, and Ag between 0.6 to 5.6 ppm.1  


    Agreement Terms 

    Radius has entered into an option agreement with a local Mexican group to acquire 100% of the 200 ha Tropico claim. Payment on signing (completed) US$200,000 can be paid in 6 monthly installments over a period of 42 months, starting with $25,000 at month 12 from signing in order to maintain the property option. At month 48, Radius can acquire 100% of the property for US$5,000,000. An additional milestone payment of $5 million is conditional on delivering a complaint feasibility study or at the start of mine construction. A further US$3 million to be paid if reserves exceed 2 million gold equivalent (Au + Ag) ounces. If Radius does not compete payment of the milestone $5 million dollars within 8 years of signing, the property would return 100% to original owners.1


    Quality Assurance and Quality Control 

    Reported assays are rock chip samples takes by Radius geologists. Reported samples were delivered to ALS in Chihuahua. The samples were analyzed by ALS Geochemistry for Au by fire assay (Au-ICP21), and Ag and multi-elements using a four-acid digestions with ICP-AES finish (ME-ICP61). ALS Geochemistry is an internationally certified laboratory. Radius routinely inserts multi-element geochemical standards and into the sample stream to monitor laboratory performance. Quality control samples submitted were returned within acceptable limits.


    Quality Assurance and Quality Control 

    Bruce Smith, M.Sc. (Geology), a member of the Australian Institute of Geoscientists, is a Radius' Qualified Person as defined by National Instrument 43-101 - Standards of Disclosure for Mineral Projects. Mr. Smith collected the samples on site at Tropico and approved the technical information contained in this website. 

    Please see Radius Gold Inc. News Release: Radius Gold discovers gold mineralized "hotspring type" sinter and breccia pipe target in Fresnillo district, Zacatecas," March 21, 2023. 

    *MAG Silver PEA November 7, 2017.