() is focused on exploring and drill testing the Bramaderos Gold-Copper Project and the El Palmar Copper-Gold Project in Ecuador, which are highly prospective for the discovery of large gold-copper systems.
The Sunstone team’s previous work in Ecuador and overseas has led to significant discoveries and shareholder value growth, and the team is working towards repeating that success at Bramaderos and El Palmar.
Sunstone’s ongoing drill program at Bramaderos continues to deliver broad gold-copper intervals, with an initial resource estimate planned in early 2022.
Location of Sunstone’s Bramaderos and El Palmar projects, Ecuador.
During FY20-21, Sunstone monetised a portion of its investment in Swedish listed exploration company, Copperstone Resources AB, which realised cash of about A$17 million through the sale of shares and agreeing to an early payout.
As at June 30, 2021, Sunstone held A$12.2 million in cash and the value of its remaining interest in Copperstone was A$11.6 million, providing a well-funded balance sheet to continue exploration and drilling.
The Bramaderos Project (87.5% owned by Sunstone) is in Loja province, southern Ecuador, 90 kilometres from the city of Loja and is highly prospective for the discovery of large gold-copper deposits.
Easy access is provided by the sealed Pan American Highway that crosses the western part of the concession.
The area has nearby available hydro-power and gentle topography with an average elevation of around 1,100 metres above sea level.
Gold and copper mineralisation outcrops at surface with multiple targets defined and strengthened based on the integration of exploration data.
The defined areas of interest comprise six targets for porphyry gold-copper and several targets for epithermal silver-gold and base metal mineralisation.
Brama target drilling
At the Brama target within Bramaderos, a large complex magnetic body has been modelled with a vertical depth of 1 kilometre.
Sunstone’s ongoing drill program at Brama continues to deliver significant broad gold-copper intervals.
The drill program will continue through to December 2021, after which all data will be compiled, and an initial resource estimate will be undertaken in early 2022.
Earlier this month, further drilling results from holes BMDD009, 010 and 011 highlighted the potential for Brama to host a substantial gold-copper porphyry system.
Recent highlight assays include:
- BMDD009; 185.3 metres at 0.4 g/t gold, 0.15% copper, (0.64 g/t AuEq1) from 116.8 metres;
- BMDD010; 170.65 metres at 0.46 g/t gold and 0.15% copper. (0.7 g/t AuEq1) from 311.75 metres, including 69.6 metres at 0.65 g/t gold, 0.2% copper, (0.97 g/t AuEq1) from 347 metres; and
- BMDD011; 404.8 metres at 0.32 g/t gold, 0.09% copper, (0.46 g/t AuEq1) from surface, including 51.3 metres at 0.54 g/t gold, 0.07% copper (0.65 g/t AuEq1) from surface.
1AuEq is calculated on a gold and copper basis only using metals prices at August 30, 2021, being US$1,814/oz gold, US$4.36/lb copper using the formula: (gold grade in g/t) + 1.6 * (Cu grade in %).
“Resource estimate a logical next step”
Sunstone managing director Malcolm Norris said following the release of the assays: “We are very pleased with the latest round of results which provide more firm evidence that Brama has the potential to be a large gold-copper mineralised porphyry.
“Importantly we are seeing good gold-copper grades from surface.
“An initial mineral resource estimate is a logical next step for the Brama target.
“Our drilling is being guided by robust 3D geological modelling to continue to define the Brama system.
“In parallel, we are re-visiting other targets such as Limon, Playas and Melonal with a view to defining additional resources.
“Our plan is to grow the scale of the opportunity at the Bramaderos Project via exploration and mineral resource definition across several porphyry systems.”
Espiritu silver-gold target
Eleven drill holes totalling about 3,400 metres were completed during FY2021 at the Espiritu silver-gold target at Bramaderos, where results from the first trench returned encouraging high grades of silver, lead and zinc with associated gold over a width of 4 metres (415 g/t silver, 0.9 g/t gold, 6.9% zinc and 6% lead) within a broader zone of 21 metres grading 82.4 g/t silver.
Drill hole ESDD005 intersected three intervals of silver-gold-zinc-lead mineralisation including 2.4 metres at 104 g/t silver, 0.7 g/t gold, 3.4% zinc and 1.6% lead from 145.8 metres.
All data from Espiritu are now being reviewed to plan the next phase of drilling.
This will likely include drilling at Espiritu Southeast where Espiritu-style veining is present at surface and corresponds with a cluster of zinc and silver-in-soil anomalies over a strike length of 400 metres.
It is still early days in the exploration of this system and Sunstone is still developing models for the style and geometry of mineralisation, which will, in turn, enable better targeting of the higher-grade areas.
Other epithermal targets have also been identified within the Bramaderos concession and will be scheduled for further exploration and drilling.
El Palmar Project
In August 2020, Sunstone agreed to the staged acquisition of the El Palmar Copper-Gold Project as part of its strategy to expand holdings in Ecuador on projects which pass the company’s technical and commercial criteria and offer the potential for significant resource discoveries.
The property is 60 kilometres northwest of Ecuador’s capital Quito and is well serviced by several sealed highways leading to both the country’s capital and international ports.
El Palmar sits on the regionally significant Toachi Fault Zone, which hosts other porphyry copper deposits such as the 2.7 billion tonnes Alpala (Cascabel) and 1 billion tonnes Llurimagua deposits.
Broad-spaced historical exploration results had defined a 600-metre diameter area of anomalous copper and gold that has not been adequately tested with drilling.
Three diamond drill holes were completed by a previous explorer (Codelco) at El Palmar in 2012 and delivered significant intersections of copper and gold in a porphyry environment.
Sunstone has re-logged the historical drill core and identified widespread trace bornite.
The assay results together with the logging confirm a well-mineralised porphyry with the current interpretation suggesting the historical drill holes passed over the top of, and to the side of the main target zone.
Sunstone has also recently undertaken a detailed ground magnetics survey which defined a large anomaly with a diameter of ~700-metres exhibiting features consistent with a large porphyry system.
Phase 1 drilling
A phase 1, 2,000-metre drilling program commenced in August 2021 at El Palmar targeting the upper 400 metres of the magnetic feature.
The first drill hole, EPDD001, intersected a copper mineralised porphyry system from surface.
The second hole, EPDD002, returned a 250-metre intersection of copper mineralised porphyry based on visual inspection.
Drill core from EPDD002 from 305 metres to 310.2 metres exhibiting intense magnetite veinlets and quartz-magnetite-sulphide veins.
Norris said following the release of the results in early September: “The second drill hole at El Palmar appears to be well mineralised over a substantial interval, as evidenced by the photos in this release.
“Given what we have seen in the first two holes, we are increasingly optimistic about the potential at El Palmar and we are looking forward to receiving the assays.
“Hole three is now underway and planning for further drilling after this initial 2000 metres program is well advanced.”