Preliminary results from exploration at Meteoric Resources’ (ASX: MEI) Juruena gold project in Brazil have detected the presence of a large, high-response chargeability anomaly believed to be strongly indicative of disseminated sulphides.
Geophysical studies during the year including deep induced polarisation (IP) and magnetotellurics (MT) surveys located the anomaly, which is over 2,000m long, 1,500m wide, less than 500m below the surface and open to the north-west.
An intense core of high chargeability occurs within the centre of the anomaly and presents an “obvious drill target” approximately 1.5km long and 800m wide.
Given the setting – including the presence of strong copper-gold results throughout the project area – Meteoric said the IP anomaly “probably represents” a zone of disseminated sulphides at depth.
The MT data is expected to be processed and interpreted by the new year with first drilling to follow shortly after.
High-grade epithermal gold
Meteoric’s exploration team has long been struck by the potential for high-grade epithermal gold deposits at Juruena to be part of a bigger magmatic hydrothermal system.
Meteoric managing director Andrew Tunks said the massive high-response anomaly could lead to a significant porphyry copper-gold discovery.
“There is no doubt in my mind that drill testing of this massive anomaly is a potential game changer [for us],” he said.
“As soon as the survey team started to collect data on the first lines, there was evidence of a strong chargeability anomaly beneath the Mauro and Crentes prospects, at which point we were confident we were onto something exciting.”
Copper prices soaring
Speaking with Small Caps, Mr Tunks said Juruena’s potential to be a major porphyry copper-gold discovery comes at a time when “copper prices are up over 25% in 2020”.
Copper prices have been rebounding since the easing of coronavirus containment measures around the globe with firm demand being led by China, the world’s largest commodities consumer.
Prices have hit multi-year highs, peaking at US$7,735 per tonne last week and currently standing at US$7,656/t, still up almost 35% in the last six months and up 8.85% in the last month.
Earlier this month, Goldman Sachs analysts raised their 12-month forecast for copper from US$7,500/t to US$9,500/t and said it was “highly probable” that copper could reach US$10,000/t by the first half of 2022.
Copper-gold porphyry deposits
Mr Tunks used the Cadia copper-gold district being mined by Newcrest Mining (ASX: NCM) in New South Wales as an example of a “massively profitable” copper-gold porphyry deposit that annually produces around 950,000 ounces of gold and 90,000t of copper.
Porphyry deposits are considered the world’s most important source of copper, estimated to account for about 50-60% of world copper production, as well as a major source of gold.
They usually are of a lower grade, but their large size means they have the potential to contain a higher tonnage of copper and have long mine lives, making them attractive to major mining companies. Project location
The Juruena project is located at the western end of the Alta Floresta mineral province in Brazil’s Mato Grosso State, in the southern sector of the Amazon Craton.
The province has been the focus of artisanal mining and gold exploration for more than 30 years but has more recently emerged as a region for porphyry copper-molybdenite-gold, gold-copper, and gold-polymetallic after the discovery of several porphyry-like magmatic-hydrothermal systems.
In 2018, Anglo American’s discovery of the Jaca copper porphyry system in the south eastern portion of Alta Floresta led to an “exploration rush” with up to 3.5 million hectares being applied for throughout the area by junior and major resource companies.
Meteoric acquired Juruena in mid-2019 from Crusader Resources, now known as Big River Gold (ASX: BRV), and has since conducted 8,000m of diamond drilling to increase high-grade gold resources at the Dona Maria, Crentes and Querosene prospects.
The company has also pursued the search for a high-tonnage copper-gold deposit by re-logging historic diamond drill core; re-classifying lithologies to better reflect their significance in a porphyry setting; and recognising and recording classic porphyry-style hydrothermal alteration assemblages.