Making serendipity happen in the Atacama
August 22, 2022Exploration is about being in the right place at the right time and having an expert team of geologists to recognise potential and bring it to a discovery. This is our path to success at Avispa, says Dr Tony Harwood, CEO of Montero Mining.
1. Montero Mining’s Avispa copper project spans 473.3 square kilometres in the Atacama Desert, one of the richest regions on earth for copper. What are the obvious and less obvious advantages of having such an excellent address in northern Chile?
In terms of advantages, we are in one of the richest copper trends in Chile, if not the world. Exploration concessions, if you can find the right one and it’s available, are relatively inexpensive to apply for and applications are dealt with on a first come, first served basis.
Mines in Chile are usually large and have a long mine life once found and developed. There is excellent exploration and mining expertise in Chile for discovery, development and operation. Mining infrastructure is good and it’s relatively easy to secure financing in this Tier 1 mining investment destination. Because most major and mid-tier copper mining companies are mining and exploring in Chile, there are good opportunities to joint venture or sell your project.
At Avispa, the ground has been through at least one or two rounds of initial exploration by a major and a junior exploration company, with some wide-spaced reconnaissance drilling. Both companies dropped the Avispa concessions while copper prices were still low between 2018 and 2020. The project area has a cover of Quaternary and Miocene sediments and these cover the Cretaceous volcanic and sediment rocks that host the target Palaeocene porphyry copper deposits at depth. Our mapping in the south (the San Salvador valley) has shown that these cover rocks are between 20 m and 80 m thick. Hence, remote sense methods such as geophysics will be used to see through the cover and detect porphyry and copper mineralisation geochemical signatures. We are also trying to source exploration and drilling data from previous holders of the concessions.
2. The project area is 40 km north of BHP’s Spence copper-molybdenum mine and KGHM’s Sierra Gorda copper-molybdenum mine. It is 8 km south of the Chug-Chug porphyry system, which shows Quartz-Sericite-Tourmaline breccias and copper oxide mineralisation on the surface. What are the likely geological sources of the minerals found around the Avispa area?
The Spence and Sierra Gorda mines were both blind discoveries made by exploration. The host rocks to the porphyry copper mineralisation are covered with thick Miocene sediment and gravel. Geochemistry and geophysics guided exploration drilling to make the respective discoveries.
Exploration is a challenging business. Not only do you have you to be in the right location but you also need the patience to develop and then test targets with drilling. Montero has been actively sampling drill chip piles left on the surface at previous drilling sites, and having these geologically logged and chemically analysed as they may provide some indication of the subsurface rocks and mineralization, although from what depth is unknown.
Montero has submitted the samples for four acid digestion followed by trace element analysis by mass spectrometry and the results will be subjected to sophisticated geochemical algorithms that will be used to vector into prospective mineralisation at depth. Geochemistry and the research of the trace element signatures of mineralised porphyry has come a long way in recent years with exploration discovery aided by computing and machine learning.
As we indicated in our recent announcement, Montero has advanced exploration at Avispa to the point where we are starting a programme of defining and prioritising copper-drilling targets.
3. Montero has a Chilean team that is conducting field exploration at Avispa. Is their local knowledge and experience of the geology an important factor in Montero’s exploration success?
Exploration success can only be achieved by making an economic discovery. However, an economic discovery, in most cases, can only be found by a focused, skilled, well-funded and motivated exploration team that is not afraid of challenging assumptions, whether these are published maps or geological theories. Our team has knowledge and experience gained over decades and applies this in a programme to make a mineral discovery, building on the shoulders of giants. Serendipity is probably the most important unknown factor in any discovery. Our exploration team is Chilean and is therefore well versed in the geology of Chile, and this is a huge advantage. This factor, together with the global experience of our board, will significantly enhance our chances of achieving success.
4. A quarter of the world’s 870 million tonnes of copper reserves are located in Chile. How much of the Atacama is still unexplored for copper and other minerals?
There are many significant copper discoveries still to be made in the Atacama – the easy deposits close to surface have been discovered but there are huge tracts of the porphyry copper belts that have not seen detailed exploration or been explored with recent technological innovations in geochemistry and geophysics. We believe the prospectivity of this part of the Atacama is very high for copper as well as other metals still to be discovered.
5. Montero’s copper exploration concessions are adjacent to some of the world’s largest copper porphyry deposits held by some of the mining industry’s biggest players, and one of its neighbours recently made a copper discovery. Why is this good news for explorers in the region?
It is always encouraging to learn of exploration successes and that years of prospecting, with its blood, sweat and tears, has yielded a positive result. In particular, the copper discovery that is in the same porphyry belt we are exploring is very encouraging, because large mineral deposits are often nested together, and Avispa is not too far away.
6. How does the prospectivity of the Atacama region compare with that of the copper belt running across Central Africa?
I have also worked in the Central African Copperbelt of Zambia and the Democratic Republic of Congo (DRC), where major discoveries have been made and mines established. The African Copperbelt hosts a very different kind of copper deposit than those found in Chile, and the region is very different politically too. Like most of Africa, Zambia and the DRC are challenging environments to invest and work in.
7. How do junior mining and exploring companies like Montero get their hands on prospective copper concessions in good mining jurisdictions when demand for copper is set to grow?
Juniors are nimble and can work fast. Skills and experience are a must but serendipity plays a major part – being in the right place at the right time is as important in exploration as it is in life.