Early stage exploration at Inca Minerals’ newly-acquired Riqueza project seems to have vindicated the company’s move to high grade at-surface mineralisation away from lower-grade mineralisation that proved tantalisingly out of reach at its previous Chanape copper porphyry project. 

Assays from sampling at Riqueza’s two key prospects, Humaspunco and Uchpanga, have just revealed strong zinc and lead results, bonanza silver grades, and bonus gold results of 2.65g/t.

Inca managing director Ross Brown said the results were particularly pleasing.

“We’ve identified a high grade vein at Uchpanga with fantastic numbers – 920g/t silver, or 29oz/t, 20.96% zinc, 16.71% lead and 2.65g/t gold,” he said.

“This vein, identified in an old working, is believed to be associated with a gossan which has been mapped recently over 750m.

“Gossan is a type of iron-oxide rich rock that represents highly weathered sulphide mineralisation. It’s what we field geologists look for – dark coloured grungy looking crud that just below the surface becomes shiny fresh sulphides.”

Riqueza is first and foremost a zinc-silver-lead project but now it has solid gold credentials as well.

“It certainly adds an exciting extra dimension to this rapidly expanding project,” Brown said.

At first glance, Inca seems to have perfect timing in picking up a highly-promising zinc project, just as its key Chanape copper project veered towards the too-hard basket due to the depth and complexity of the enormous porphyry system.

But that glance belies the work put in by the Inca team who have been watching the increasingly encouraging zinc space over the past 18 months and negotiated the terms for Riqueza over a similar period.

After drilling 1000m deep holes at Chanape, Brown is delighted with the simplicity, high-grade and near-surface mineralisation at Riqueza.

The 73 initial rock chip samples of a manto deposit at Riqueza’s Humaspunco prospect averaged more than 7% zinc, 200g/t silver and 10% lead, including a peak value of 43.5% zinc, 2,668g/t silver and 48.7% lead.

Inca has moved quickly to apply for four new concessions surrounding Riqueza, which will bring the project area to a total of 4,600ha.

“There’s no point in crowing over a porphyry discovery if the payable part of the porphyry is out of reach,” Brown said.

“We may gain a modicum of credit for making a genuine porphyry discovery when discoveries are few and far between but I’m more interested in crediting the company with a new high-grade project with real economic potential. It’s a good start when you can walk on visible mineralisation.”

Analysts are also tipping zinc prices to improve in a case of “not if, but when” supplies run low. Zinc recently posted its longest streak of gains in two years.

Peru is an established zinc mining destination, with a number of mines and processing infrastructure in the mineral-rich central belt of the country, such as Antamina, Cerro De Pasco and Pallancata.

“Peru has the third highest producer of zinc in the world and has the third largest zinc resource in the world, on both counts, third only to China and Australia,” Brown said.

“We know Peru, we know the permitting process; we know that social licence is important [and] we’re very comfortable operating there.”

The decision to move away from Chanape was also made easier thanks to a site visit by porphyry expert Richard Sillitoe. The visit was enabled through Inca’s biggest shareholder – mining-focused private equity firm Resource Capital Funds (RCF VI), who know Sillitoe. 

“The story that has unfolded at Chanape is one that has tracked a technical success, chapter upon chapter of exciting exploration news. Richard however confirmed that the story is unlikely to conclude with an economic success. Certainly an anti-climax,” Brown said.

There’s a sequence to this story. It’s called Riqueza.

The Riqueza project acquisition, which is costing Inca a total of US$1.773 million over a five-year agreement, with modest exploration requirements, has come about through Inca’s Peruvian connections.

“Our network of geologists and businessmen in Peru provides us access to many great opportunities that don’t see the light of day in West Perth,” Brown said.

“We are still looking for opportunities in the zinc space. There’s plenty in Peru when you know where to look.”

Brown was due back in Peru, shortly after speaking with Mining Journal, and said the company was keeping an eye out for more zinc opportunities in the South American country.

“We have another zinc project called Cerro Rayas, which has similar grades to Riqueza,” Brown said.

“It has mineralisation over a 1.2km strike length and we’ll be looking to develop this project at the same time as Riqueza.

“Riqueza and Cerro Rayas are both high-grade zinc projects. I reckon Inca will be poised to make the most of a rising zinc market.

“We’re in the right place at the right time.”

Major shareholder RCF VI has also backed Inca’s decision to shift to zinc, upping its stake from an initial 12% to 18% in late May.

“They like Riqueza so they’ve increased their stake in the company. I’d say that’s an endorsement of our move to zinc,” Brown said.

The company has also completed a number of smaller placements to lock in extra funds to kick start exploration at Riqueza.

Aside from zinc, Brown is also excited by Riqueza’s precious metal potential.

“As a board, we think zinc is a good thing and I’m particularly interested in the combination of zinc and silver – I reckon silver will have its day too,” he said.

“A lot of people are rightly excited about lithium but silver has a myriad of uses, from batteries to currency, electronics and biocidal uses in medicine. Could silver be the next lithium? I think so. Just consider silver-oxide batteries – they have the highest energy/weight ratio than any other battery. Sounds like a must-have energy source where weight is an issue!”

Inca is also gaining access to historical reports on Riqueza from the project vendor, which is improving the company’s knowledge of the ground as it plans its exploration program.

Riqueza hosts two historic small-scale mine centres. One such old mine at Uchpanga and a juxtaposed extensive gossan were targeted in the recent mapping and sampling program, along with an extension of a known high-grade manto deposit at Humaspunco.

Inca is applying for a category 1 drilling permit, which Brown said could be approved within four months of application and could allow for up to 20 drilling platforms and an unlimited number of holes.

“The permitting process has become a lot less problematic,” Brown noted.

“All parties concerned are more familiar with the rigours of the regulations, a raft of which were put in place in 2011/2012. A balance between social and environmental considerations and mining and exploration has been achieved. It’s game on in Peru.

“We’ve started the permitting process already, which will run in parallel with our sampling and geophysics programs.

“We have no shortage of existing very high-grade targets but we are not limiting ourselves to these. Geophysics will give us a very good idea as to what sits below the surface. Based on the widespread nature of mineralisation at the surface, we should find plenty at depth.

“We expect a steady news flow for investors and shareholders over the coming months leading up to drilling.”

Brown said he felt a weight was lifted off his shoulders, moving from the enormity of Chanape to the simplicity of Riqueza, with its strong grades, visible and straightforward mineralisation and multiple commodities.

“We’re already getting grades in double digit figures and in multiple percentages and we’re yet to start drilling,” he said.

“Strong mineralisation in over a dozen vein, manto, dyke and breccia deposits, and now gold mineralisation in our largest mineralised feature – a 750m long gossan – greatly enhances Riqueza’s prospectivity.

“As we work our way into this project I think the results will ignite a spark in Inca. A new beginning, a new commodity, sniffs of the turn-around in the market, exploration on the rebound, plenty of targets, plenty of news, plenty of zinc – it’s exploration in its purest and most exciting form.”