VMS vs. Porphyry and Sediment Hosted Copper Deposits: Understanding GreenTech Metals' Whundo Copper Play

In the world of copper exploration, it’s all about knowing your deposits. From porphyry to sediment hosted to volcanogenic massive sulphide (VMS), different types bring unique opportunities and challenges. For GreenTech Metals and its Whundo Copper Project in the West Pilbara, Western Australia, the focus is on VMS deposits—high-grade, polymetallic systems that can punch well above their weight.

Supported by seasoned geologist and technical advisor Julian Hanna, who indirectly helped put Sandfire Resources on the global map when it acquired the Motheo Copper Project in Botswana from MOD Resources in October 2019, GreenTech is betting big on Whundo’s VMS potential. But why the excitement about VMS deposits in particular? And how do they stack up against the copper industry’s two behemoths: porphyry and sediment hosted copper deposits?

What’s So Special About VMS Deposits?

VMS deposits are formed from volcanic and hydrothermal activity at or near ancient seafloors. Over time, metals like copper, zinc, and sometimes gold or silver are deposited as “massive sulphides.” While VMS deposits tend to be smaller than their porphyry and sediment hosted counterparts, they make up for it with one crucial factor: grade.

Typical porphyry deposits offer copper grades in the range of 0.3-0.6%, but VMS deposits can deliver much higher concentrations—often between 1-4%. For explorers like GreenTech Metals, who are looking for fast returns and rich veins, VMS deposits offer that tantalising mix of high-grade ore and multi-metal revenue streams with the focus firmly on the Whundo Copper Project which is a largely overlooked 2km long VMS system located just 40km south of Karratha in WA’s Pilbara region.

Julian Hanna is no stranger to a good copper deposit. His experience over 7 years as Managing Director of MOD Resources when it discovered, drilled out and completed a feasibility study on the sediment hosted Motheo Copper Project, has made him a believer in copper.  His experience in building MOD’s Botswana sediment hosted copper discoveries which were then developed by Sandfire into the 5.2Mtpa Motheo mining operation has confirmed his belief in the ability for copper to deliver outsized returns. And he’s seeing similar opportunities at GreenTech’s Whundo Copper Project.

“Whundo is shaping up as a classic VMS deposit, with solid copper grades and the added bonus of zinc, silver and potentially gold by-products,” says Hanna. “The early results we’ve seen are mostly from shallow historic drilling and EM surveys along a 2km long zone of copper and zinc mineralisation which shows we’re in the right place, and we’re confident there’s more to find.”

VMS vs. Porphyry and Sediment Hosted Copper

When it comes to copper mining, porphyry and sediment hosted deposits are the industry’s workhorses. These large copper systems can stretch up to billions of tonnes, offering decades of mining life. However, what they have in scale, they generally lack the grades seen in VMS deposits. The average copper grades for porphyry and sediment hosted deposits range from around 0.3-1.5%, which is often enough for copper majors to develop into large-scale, high capex operations.

In contrast, VMS deposits tend to be much smaller—often just a few million tonnes—but with much richer ore. These higher grades (closer to 2-3% copper) mean smaller mining footprints, shorter permitting timelines, lower development costs and quicker returns, which is why VMS deposits are prized by mid-tier miners and smaller explorers like GreenTech. You don’t need huge tonnes to make a project like Whundo profitable, but you do need high-grade ore. 

 What’s Happening at Whundo?

GreenTech Metals’ Whundo Copper Project is in the West Pilbara, an area rich in mining infrastructure and resources. VMS deposits often occur in clusters, meaning Whundo’s location has the added potential of nearby discoveries that could boost the overall prospectivity.  

Historic activities at Whundo include shallow open pit mining of copper oxide ore at the southern end of the Whundo VMS deposit (where around 85% of drilling and the current mineral resource is located) and underground mining of high-grade shallow copper ore at Yannery 1.2km north of the open pits. 

Further north, at the limit of drilling at Whundo, previously reported results include an intersection of 23.7m @ 3.2% copper, 200m down-dip below an intersection of 34m @ 4.4% zinc.  This northern-most drilling not only demonstrates high copper and zinc grades and metal zonation common to VMS deposits, it also opens up potential for additional high grade mineralisation even further north within GreenTech’s mining lease where the prospective VMS contact is buried under shallow cover.  On 19 September 2024, Greentech announced it had identified a highly conductive EM plate interpreted to extend >400m down-dip and below any previous drilling at Shelby, in the centre of the Whundo VMS system. Not surprisingly this is one of the first targets planned to be tested in the next round of drilling.

Recent drill results at Whundo have already returned copper grades of 1-2%, firmly in line with other VMS operations. Alongside the copper, there’s also significant zinc—a critical metal in its own right, with rising demand from battery manufacturing and renewable energy.  What also needs to be considered is that 91% of all drilling to date at Whundo is less than 150m deep – very shallow compared with other Australian and global VMS deposits.  This also means that possible extensions to the known copper and zinc mineralised bodies drilled to shallow depth and the large Shelby EM conductor plate at Whundo remain untested. 

A big part of Whundo’s appeal is its location only 40km south of Karratha along a two-lane sealed road. Unlike some VMS deposits found in remote or challenging terrain, Whundo benefits from good access to infrastructure.

Proximity to roads, established accommodation, an airport with multiple daily flights to Perth, export ports, and even processing facilities in the Pilbara means GreenTech would be unlikely to incur high start-up infrastructure costs and related permitting delays to bring Whundo into production.

VMS: High-Grade Winners in the Copper Space

VMS deposits might not boast the scale of porphyry or sediment hosted copper projects, but they’ve proven their worth time and again in Australia. Take the Golden Grove mine, for example, which has been producing copper, zinc, and precious metals for decades at grades between 1-2%. Or DeGrussa, where Sandfire’s discovery of high-grade copper in the early 2010’s gave that company its start to becoming one of Australia’s premier copper mining companies.

The secret sauce of VMS deposits is their polymetallic nature. Along with copper, they often contain significant amounts of zinc, lead, and even gold or silver, offering multiple revenue streams. This diversification acts as a hedge against fluctuating commodity prices, giving miners more flexibility in lean times.

With strong early results, a well-located project, and the expertise of Julian Hanna and the exploration team based in Karratha, GreenTech Metals is well positioned to advance the Whundo Copper Project. Hanna’s belief in the project’s potential is clear: “We believe Whundo may have the potential to develop into a significant producer in the region. The grades are there, the geology is in our favour, and we are in a very fortunate position in having substantial infrastructure nearby to help make this project work.”

As global copper demand continues to climb, driven by electrification, renewable energy, and infrastructure projects, high-grade deposits like Whundo will only become more valuable. With copper prices hovering around US$4.40 per pound and analysts predicting future gains, GreenTech is advancing Whundo at an opportune time.  For companies like GreenTech Metals, owning 100% of a VMS deposit with significant upside potential can be transformative. With Whundo’s promising grades and polymetallic potential, GreenTech could very well be on its way to joining the ranks of Australia’s VMS success stories, proving that when it comes to copper, sometimes smaller—and higher-grade—is better.