Project of the Week: Los Osos, Ecuador

September 24, 2020


Featured Image: A completely unrelated (but stunning) photo from the mountains of Ecuador (Credit: Jaime Serrano)

By Esme Whitehouse.

This week I spoke to Merlin Marr-Johnson of Salazar Resources (TSXV:SRL) about their Los Osos project in Ecuador. The company focus on exploration and development of projects in Ecuador and Colombia, where they have proved their discovery prowess on several deposits such as Curipamba and Fruta Del Norte. They currently have a number of 100% owned projects in both countries, including Los Osos, and a JV with Adventus Mining (TSXV:ADZN, OTCQX:ADVZF) at Curipamba.

Los Osos is a 229 ha project area located in the Cerro Pelado-Cangrejos mining district, southwest Ecuador (Figure 1). The property is home to Au-Ag vein systems, hydrothermal breccias, Au-Cu porphyries and several quartz-tourmaline breccias with pyrrhotite and chalcopyrite mineralisation. Some of the veins were targeted by small-scale artisanal miners in the past and historic data includes geological mapping, sampling, and airborne geophysics.

Figure 1. The location of Salazar Resources’ Los Osos Cu-Au project.
Figure 1. The location of Salazar Resources’ Los Osos Cu-Au project.

The choice to explore Los Osos stems from a good understanding of the prospectivity of the wider area as Pacho Soria (Salazar’s Exploration Manager) back in the 1990s led the exploration team that discovered the Cangrejos 17 million ounce deposit just to the north (now owned by Lumina Gold, TSXV:LUM). Not only that but high-grade results have been reported from licences adjacent to Salazar’s project now held by Challenger Exploration (CEL.ASX). To the east is El Guayabo that reports historic assays of 2.6 g/t Au, 9.7 g/t Ag , and 0.2% Cu over 156 m. To the north is Colorado V that reports results from re-assayed historic drill holes of 1.5 g/t Au and 1.8 g/t Ag over 146 m.

This means the exciting potential of the wider area around Salazar’s project is both recognised and possibly underappreciated. But what about Los Osos itself?

Primarily, the project area is composed of metamorphic rocks with Tertiary intrusions. There is correlation between the age of intrusion here and that of the giant Chilean Cu-Au porphyries. Pyrite and chalcopyrite mineralisation are observed to be extensive in the porphyries, metamorphic rocks, and hydrothermal breccias present at Los Osos. Gold and copper grades seemingly correlate with intensity of sulphide mineralisation and intensity increases further with alteration.

Work at Los Osos has continued through the Covid-19 pandemic. They are lucky enough to have a highly experienced field technician living close to the area who was able to work safely even during the lockdown. During the global downtime Salazar completed a mapping and soil sampling program. Results corroborated an earlier understanding that the area is pervasively mineralised, with results especially continuous in the breccias. Two mineralisation styles were found in the area. The first is porphyritic intrusions in metasediments with up to 14.5g/t Au and the second is breccia bodies with continuous mineralisation with up to 4.5g/t Au. Narrow veins that have been extensively mined by artisanals in the northeast of the concession returned very high grades when sampled, but Salazar do not regard these as a priority exploration target.

Instead Salazar plans to target the potentially high bulk tonnage hydrothermal breccias and the roof of a porphyry. They will do so with a drill program that is set to commence very soon. They will drill 10 holes amounting to 5000 m. The first 5 holes are planned and the subsequent 5 will be sited once results are returned (Figure 2). Some breccia bodies are up to 300 m x 200 m.

Figure 2. Proposed drill-hole traces, soil anomalies and key geological features, Los Osos
Figure 2. Proposed drill-hole traces, soil anomalies and key geological features, Los Osos

Merlin even gave me the pleasure of showing me a sample of the sulphide-mineralised breccia from Los Osos (Figure 3). It’s not the same seeing rocks over a video camera, but after so long out of the field it was pretty exciting.

Figure 3. Fresh from the field, a hand specimen, hydrothermal breccia, Los Osos
Figure 3. Fresh from the field, a hand specimen, hydrothermal breccia, Los Osos

Often a key concern with projects in South America is the environmental impact and the social licence to operate. Across Ecuador the environmental and social challenges vary enormously, with many areas opposing mining activity.  Los Osos, as it happens, is located in a mining area and rather than being specifically anti-mining, community concerns are centred around the availability of employment and the opportunities for local artisanal miners. Accordingly, Salazar is working on a sub-agreement with a small-scale miner to enable operations on the high-grade narrow underground veins to continue. The Ecuador government has elevated the status of the mining industry to a strategic sector and are hoping to increase the contribution of their mining sector to generate 4% of GDP by 2021 [1] [2].

See you next week!


Further Information:

Salazar Resources:



[1] - Vella, H. (2019). Can Ecuador achieve its bold vision for mining? Mining Technology. 

[2] - Leotaud, V. R. (2019). Ecuador’s new mining policy backs large-scale projects. Mining. Access from:


Posted in Project of the Week

Esme Whitehouse View posts by Esme Whitehouse

BSc Geology at the University of Brighton and MSc Exploration Geology at Camborne School of Mines. Now working as a junior geologist alongside in West Africa with Origin Exploration.