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El Dovio: a 100% owned high grade copper/gold project: VMS-style mineralisation, with 34 drill hole intercepts that include 8.14g/t Au, 6.92% Cu, 39.41g/t Ag and 1.46% Zn over 5.80 metres in drill hole D13-05 and an exploration adit having been completed.


The El Dovio property hosts high grade polymetallic gold-silver-copper-zinc mineralization with grades to 104 grams gold per tonne and 17% copper hosted within a boiling “feeder zone” believed to underlie a Volcanogenic Massive Sulfide (VMS) target in an extensive belt of metamorphosed marine volcanosedimentary rocks known to host other polymetallic and (VMS) prospects and mines throughout western Colombia, Ecuador and beyond.

Work to date indicates a deposit with high unit value, exceptional metallurgical characteristics and low price sensitivity. Work by Newrange Gold Corp of Canada (Newrange) materially expanded the strike of known mineralization at El Dovio and identified a zone hosting high grade polymetallic mineralization ranging from 10 to 68 meters wide in outcrop and approximately 1 kilometer long that has locally been traced down dip more than 200 meters below outcrop with diamond drilling.

Mineralization remains open to additional extension on strike and at depth. Diamond drilling has confirmed the presence of prospective graphitic chert sediments with bedded massive sulfide mineralization to the east of the Sabana Blanca Zone. Coliform banded crystalline quartz and sulfides indicate active boiling during mineral deposition resulting in exceptionally high gold grades in the Sabana Blanca zone.


The El Dovio project is situated in the western range of the Colombian Andes at an elevation of approximately 1,400 meters. The El Dovio mineral licenses are 100% owned by CMC, covering more than 1,200 hectares.

Outcropping mineralization in what is now known as the Sabana Blanca zone was first discovered in 1974 but lack of access prevented exploration until the 1980’s when a road was built to the nearby hamlet of Lituania. In 1988 a short exploration adit was driven on high grade mineralization in Quebrada Soberana (Soberana Creek).

Between 1991 and 1993, 691 meters of small diameter core was drilled in 15 shallow holes. Less than 41 meters of that core was ever assayed. That work returned values averaging 5.05 g/t gold, 24.1 g/t silver, 2.14% copper and 2.00% zinc, over widths ranging from three to fifteen meters in surface, underground and drill exposures.

Work by CMC from 2009 to 2014 expanded on these results with geological mapping, geochemical and geophysical surveys and diamond core drilling. This work traced mineralization in the feeder or “stringer” zone for approximately one kilometer along strike and has identified a highly prospective bedded sulfide horizon at the Brazo 1 target zone.

Santa Blanca adit.


In their northernmost extension, the Andes divide into three main branches, the Western, Central and Eastern Cordilleras (Figure 4 1). The Western and Central Cordilleras are separated by the Cauca Valley, and the Central and the Eastern Cordilleras are separated by the Magdalena Valley, an intermontane basin. The Llanos basin marks the foreland basin between the Andes and the Guyana Shield.

Each branch of the northern Andes is characterised by its own tectonic history, linked to interactions between the Caribbean, Nazca, and South American plates. These interactions resulted in complex combinations of subduction, magmatism, terrane accretion, thrusting, and uplift as well as local extension and formation of foreland basins. Based on the geological history, it has been postulated that several terranes accreted episodically to the South American continent between the Cretaceous and the Miocene.


Mineralization at El Dovio occurs within a north-northeasterly trending belt of Cretaceous aged, volcano-sedimentary rocks termed the Cañasgordas Group, in a metallogenic belt more than 800 kilometers long known to host a number of gold-bearing polymetallic and VMS deposits.

The Cañasgordas Group is composed dominantly of thoelitic basalts, andesites and diabase referred to as the Barroso Formation interbedded with sedimentary units composed of mudstone, shale, sandstone, greywacke, chert and minor limestone.

High grade mineralization at El Dovio occurs as structurally controlled veins surrounded by broad zones of stockwork mineralization within metamorphosed mafic volcanic rocks. This style of mineralization is characteristic of the stringer zones known to occur beneath VMS systems.

During 2014, drilling encountered bedded sulfide mineralization indicative of a VMS system in the Brazo 1 zone. Bedded sulfide mineralization at Brazo 1 consists of finely bedded pyrite with traces of chalcopyrite and sphalerite in thin bedded carbonaceous chert sediments overlying metamorphosed volcanic rocks in substantially the same geologic environment found at Mina El Roble. At Atico Mining’s (TSX-V: ATY) Mina El Roble VMS deposit, high grade, bedded sulfide mineralization occurs in carbonaceous sedimentary chert just above the contact with underlying metamorphosed volcanic rocks.

Regional Geological map.

Diamond core from Sabana Blanca. Surface Diamond Drill Hole D13-02. Mineralised intersection of 6.65m @ 4.79g/t Au, 5.56% Cu, 28.36g/t Ag and 0.29% Zn).


To date CMC has completed geologic mapping, ground based magnetics geophysical survey, ground based geochemistry, Mobile Metal Ion (MMI) surveys, rock geochemistry, saw cut channel sampling and more than 3,000 meters of surface and underground diamond core drilling in the Sabana Blanca zone at El Dovio.

Trenching and sampling has also identified mineralisation at the Granizales, Sopatrana, Silencio and Brazo 1 zones which require follow up surface exploration and diamond drilling.

Exploration results to date indicate potential for an underground, high grade, low cost mine using adit access, mechanised stoping and ore extraction via gravity. Andean propose to use dry tailings stacking which is an accepted practice in Colombia and is the preferred tailings management system in Colombia. Andean Mining’s strategy is to target a 1,000 tpd operation with expected CAPEX of US$50-US$70m.

There is potential for a larger tonnage project mining lower grade halo around high grade mineralisation.

Andean Mining’s immediate exploration strategy is to undertake in-fill and extension drilling on the Sabana Blanca zone with a view to determining a maiden JORC resource within 2 years of listing and continue exploration at the other known mineralised occurrences at Sopatrana, Silencio, Granizales and Brazo 1.

Underground and Trench sampling, Sabana Blanca adit.

El Dovio Geology map.


Andean Mining completed a scoping level study on a bulk sample taken from the adit at Sabana Blanca. The study aim was to complete differential rougher and cleaner flotation testing to produce separate copper and zinc concentrates from the massive sulfide polymetallic ore. Comminution testing was also completed to provided data for crushing and grinding circuit design. This testing set out to establish a flow sheet that can be used to test variability samples and estimate metal recovery and grade.

The composite sample received by the laboratory on Denver, Colorado, contained high levels of gold and copper. The sample assayed 16.4 g/mt Au, 32 g/mt Ag, 6.4% Cu, 0.9% Zn and 11.2% STotal. The sample is a massive sulfide with most of the sulfur present as sulfide sulfur. The majority of the sulfides are in the form of chalcopyrite and pyrite, with lower amounts of pyrrhotite and sphalerite. The head assay values and the XRD results were in good agreement.

A Bond’s Ball Mill Work Index (BWi) was determined for the supplied sample at a closed size of 100 mesh (150 microns). The work index of the sample was 15.55 kWh/st. The results indicate that the sample would be considered hard.

A Bond Abrasion Index (Ai) was determined for the supplied sample. The abrasion index of the sample was 0.798. The results indicate that the sample would be considered abrasive.

A Crusher Work Index (CWi) was determined for the supplied sample. The crusher index of the sample was 12.2 kWh/st. The results indicate that the sample would be considered medium hardness.

The differential flotation approach floated nearly all of the metals contained in the sample. Each individual metal recovery was generally around 95% once all concentrates were combined, which is consistent with previous bulk flotation results conducted by Newrange.

The majority of the gold and silver present in the sample reported to the copper concentrate. Approximately 93.6% of the gold and 86.0% of the silver reported to the copper concentrate in test FT6. This will have a positive effect on cashflow from any operation established at El Dovio.