Ecuador explorer Sunstone Metals has a big year ahead as the true potential of its exciting Limon gold-silver discovery continues to unfold.
The company already has a sizeable porphyry resource of 2.7 million ounces of gold equivalent and a porphyry exploration target of 3.3-8.6Moz of gold equivalent at its Brama-Alba deposit at the Bramaderos project in southern Ecuador.
But it’s the discovery of the Limon epithermal gold-silver discovery that has made things interesting for the company.
Last year, Sunstone conducted an initial 10,000m drilling program 2.7km northeast of Brama-Alba, reporting a hit of 177m at 1.1 gram per tonne gold equivalent, including 15m at 4g/t gold equivalent, in March.
“Phenomenal discovery, mineralisation from surface and we really only looked at zero to 300m depth,” Sunstone managing director Malcolm Norris said.
“That [drilling] enabled us to put out the exploration target.”
The company announced an initial exploration target of 0.9-1.7Moz of gold equivalent in November to little fanfare.
As a result of the worsening market conditions for junior explorers, it temporarily stopped drilling.
“But we went into a program of trenching and that's what we're still doing at the moment,” Norris said.
“And, you know, some people sort of roll their eyes at trenching, which is not really justified because our mineralisation is from surface and they're very rigorous trenches.”
In fact, independent consultants were very comfortable using trenching results as a component of the Brama-Alba resource.
“So we're using this period to trench and try to find the edges of the system because it's bigger than we thought it was, and in the process, do it in a manner where that will lead into the mineral resource estimate.”
At the end of January, Sunstone reported new trenching results from Limon with grades of up to 16g/t gold and 376g/t silver.
The trenching results were spread across a 1.7km by 700m area and provided further evidence that Limon hosted multiple epithermal centres.
“News flow over the next couple of months is all about trenching and that's all about trying to demonstrate how potentially big this is,” Norris said.
Sunstone will then resume drilling, which will initially focus on the areas under the trenches that haven’t been drilled.
“Then that puts us in a position for the third phase, which is drilling for a mineral resource,” Norris said.
“We're probably talking six to nine months from now with good news flow the whole way, with ultimately, the concept of a mineral resource.”
Early development opportunity
Sunstone sees the potential for an early gold-silver development at Limon, which would eventually fund a larger porphyry mine at Bramaderos.
“It's the perfect staged development opportunity and I know, speaking to a number of the majors, that's what they're looking for at the moment,” Norris said.
“They don't want to be faced with a billion dollar-plus capex upfront, particularly on a project that might be in a country where they haven't worked a lot before.”
Fruta Del Norte
Ecuador is already home to a large epithermal gold mine, which is one of the most profitable in the world.
Lundin Gold’s Fruta Del Norte (FDN) mine attracted Newcrest Mining as a 34% shareholder, an investment recently inherited by new owner Newmont Corporation.
It’s not hard to see why Newcrest was attracted. FDN produced more than 481,000oz of gold in 2023 at an eye-watering head grade of 10g/t gold and has been guided to produce 450,000-500,000oz at all-in sustaining costs of US$820-890 an ounce this year.
While Limon isn’t in the same belt as FDN, mineralisation is the same geological style.
“It gives a good example of the potential for these things – they can be very high-grade, they can be large and the grade makes them highly profitable,” Norris said.
Ecuador
FDN is also a good example of the ability to get a mine permitted and built in the relatively new mining jurisdiction of Ecuador.
“I don't think people appreciate that they're actually in the headwaters of the Amazon and so it was a really good job that they did to get it fully permitted and to have retained such strong community support,” Norris said.
While popular Ecuador president Daniel Noboa is pro-mining, the country has been in the headlines for the wrong reasons lately.
There has been social unrest due to a government crackdown on the transport of drugs from neighbouring countries but Norris said the situation was easing.
Ecuador has also been a hot spot for global majors, with BHP, Anglo American, Barrick Gold and Hancock Prospecting all active.
Norris caught up with BHP’s in-country team on his recent visit to Ecuador late last year.
“They say ‘we view this as a country with great opportunity’,” Norris said.
“It's not a 12-month assessment, it's a decade-long assessment so they're definitely there for the long haul.”
