Chunibas Project

Latest News: San Marco Announces Drilling Has Commenced at the Chunibas Cu-AG Project (NOVEMBER 6, 2018)

  • Diamond drilling has commenced at Chunibas copper-silver project, located in Sonora State, Mexico.
  • san Marco and a wholly-owned subsidiary of Antofagasta plc have entered into an earn-in agreement to jointly explore and drill test several copper-silver rich mineralized targets.
  • The focus of this drilling will be to confirm the down-dip and along strike projections of high-grade copper-silver mineralization and test for the presence of additional mineralized mantos.
  • An initial 1,500 metres over 6 holes is scheduled with the possibility that additional drilling may be conducted, based on initial results.
  • Chunibas represents a typical volcanic-hosted copper-silver stratiform system which was previously unexplored.
  • Recent surface work included 38 rock chip samples, of which 26% assayed greater than 1% copper and 50% greater than 0.2% copper (see news release dated January 16, 2018).


Size:530 hectares concession
Metals:Copper, Silver
Status:Optioned to Antofagasta PLC
Stage:Initial drill program in October 2018
Location:Located approximately 160 km east of Hermosillo in the prolific Sierra Madre Occidental gold belt, Sonora State, Mexico. The Chunibas property is accessible from Hermosillo in a 3-hour drive on paved and well-maintained gravel roads.
Infrastructure:All year round water supply and high tension power lines are located on or near the property. The nearby town of Sahuaripa (pop. 3,000), has services such as electricity, water, hotels, banks, restaurants, and gas station.
Mines close by:The property is located in close proximity to several operating mines: Mulatos (Alamos Gold), La India (Agnico Eagle) and Dolores Mines (Pan American Silver).

Chunibas SW Discovery Highlights

San Marco has discovered high-grade Copper/Silver mineralization in an area on the Chunibas Project that has seen little exploration in the past.

Chunibas hosts a stratiform, volcanic hosted copper/silver zone. The stratiform, volcanic hosted style of mineralization seen at Chunibas shares remarkable similarities to productive copper-silver deposits in Chile but has no comparison in Mexico. An independent geological expert in this style of mineralization recently confirmed to San Marco that the mineralization is identical to that of the copper-silver systems in northern Chile. This suggests that the processes responsible for development of the Chilean ore deposits (such as the ones from Mantos Blancos district) may have also occurred at Chunibas.

Observed similarities between the Chunibas copper/silver mineralization and known and comparable Chilean systems include:

  • Mineralized top and bottoms of intermediate volcanic rock units. Mineralized volcanics at Chunibas display brecciation and vesicles similar to Chilean deposits.
  • High grade and stratiform-like mineralization with variable dimensions along strike and down-dip.
  • Non-supergene specularite-bornite-chalcocite-(digenite) and covellite assemblage and paragenesis.
  • Early stage alteration assemblage is comprised by epidote-chlorite-quartz-specularite.

Mineralized outcrops are difficult to sample due to their craggy and erratic nature. Where continuous chip channel sampling over stratiform units could be completed, examples assays results from the discovery zone are;

  • 10.5 metres of 1.13% copper and 16.91 g/t silver
  • 7 metres of 2.19% copper and 27.3 g/t silver.

Ongoing exploration in preparation for drilling includes;

  • Continued detailed geological mapping over the entire 1.7 km of known strike length. Mineralized volcanic units tend to have slightly varied composition and fabrics compared to less mineralized units, therefore, detailed mapping of individual units is important. In addition, mapping efforts are focused on the identification and distribution of different copper sulphides since these (similar types of Chilean systems) show specific zoning of different forms of copper mineralization.
  • Hand trenching outward from known mineralized outcrops with the intention of defining the continuity between and within the multiple mineralized units and between current surface exposures.
  • An XRF (X-ray fluorescence) rock (outcrop) analysis program for copper/silver over every outcrop within the known extensions of the mineralized corridor. Handheld XRF units provide immediate geochemical analysis (similar but more qualitative than a laboratory assay) of rock exposures. This technique is widely used by exploration companies for fast analysis of metals and pathfinder elements.

Project Geology

The Chunibas property is located in the Sierra Madre Occidental area of Northern Mexico. The property area is more specifically located in the Sahuaripa District, which geologically consists of Cretaceous to Tertiary sedimentary and volcanic sequences. Marine sedimentary limestones, sandstones and siltstones belonging to the Lower Cretaceous El Palmar Formation are stratigraphically followed by Upper Cretaceous agglomerates, sandstones, and andesite tuffs. These El Palmar Formation sediments have been structurally sheared and thrust-faulted over the more recent sediments and andesite tuffs.

Overlaying the marine sediments and tuffs are a series of volcano-sedimentary rocks and andesitic flows. Regionally, this stratigraphy is known as the “Lower Volcanic Sequence”. Upper Cretaceous to Lower Tertiary granodiorite and andesite porphyries intrude these earlier marine sediment and volcano-sedimentary sequences. A Tertiary sequence of andesite-basalt flows and rhyolite tuffs known as the “Upper Volcanic Sequence” (likely post-mineral) overlays this stratigraphy.

Regionally, these units, particularly the interface between the Lower and Upper Volcanic Sequences, host several significant gold and silver deposits including the Mulatos, Dolores and La India mines amongst others.

Santa Fe Drill Results

Drill Hole From [m]To [m]Interval [m]Gold[g/t]
And109.00110.201.202.42 (last sample at the end of the hole)
And118.00120.202.206.74 (last sample at the end of the hole)
CHD-040.00201.00All brecciaHigh Arsenic/ Antimony. Low gold values.
CHD- drilled into andesite roof pendant

All holes are drilled at – 60 inclination. CHD-01 azimuth (“az”) 90 degrees; CHD-02 az 305 degrees; CHD-03 az 90 degrees; CHD-04 az 90 degrees; CHD-05 az. 90 degrees; and CHD-06 az 315 degrees. True widths are presently unknown, as the discovery holes do not have enough information yet to identify where the holes are located in the mineralized system.

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