MineGuessr – Trimouns, France: World’s Largest Talc Quarry in the Pyrenees

Overview & location

From space, Trimouns looks unlike any metal mine in the MineGuessr calendar: a bright, amphitheatre-shaped excavation cut into a Pyrenean mountainside, with terraced benches stepping up towards the ridge and waste tips feathered down the slope. Over time the timelapse captures how a relatively modest open pit becomes a very large, multi-bench industrial mineral quarry with carefully managed waste dumps and a distinctive access road zig-zagging up from the valley.

Today, Trimouns – also known as the Carrière de talc de Trimouns – is recognised as the world’s largest working open-pit talc quarry, producing about 400,000 tonnes of talc per year and accounting for roughly 10% of global talc output. It has been in industrial production since 1905 and remains a flagship asset in Imerys’ talc portfolio.

Where in the world is Trimouns?

Trimouns sits high in the French Pyrenees, above the Ax valley in the commune of Luzenac, Ariège department, Occitanie, around 130 km south of Toulouse. The quarry lies at roughly 1,700–1,800 m above sea level, on the flank of the Saint-Barthélemy massif, while the processing plant is down in the village of Luzenac.

The operating set-up is characteristic of Alpine and Pyrenean industrial mineral sites:

• High-altitude open pit: Mining can generally only be carried out from about April to November due to snow and winter conditions.
• Valley-floor processing: The quarried talc-bearing rock is crushed on site and transported down to the Luzenac plant, which runs year-round.
• Cableway logistics: A dedicated cableway of roughly 5.5 km carries ore or crushed rock down the mountain, significantly reducing truck traffic and associated greenhouse-gas emissions on the narrow mountain road.

Geology & deposit type

Trimouns is a giant talc–chlorite industrial mineral deposit hosted in Paleozoic metamorphic rocks of the Pyrenees. It is a benchmark example of metasomatic replacement of carbonate and silicate rocks along a major fault zone.

Key geological features:

• The orebody consists of thick lenses of talc and chlorite developed at the contact between dolomitic marbles (dolostones) and overlying micaschists and pegmatites.
• The deposit formed during Cretaceous (Albian) Mg-rich metasomatism linked to crustal hyperextension in the Pyrenean domain – a classic example of large-scale fluid–rock interaction.
• Individual talc-rich zones can reach tens of metres in thickness; overall, Trimouns is described as the largest talc deposit in the world, with tens of millions of tonnes of remaining reserves and resources.

For MineGuessr, Trimouns represents the industrial-minerals end of the calendar – in contrast to the porphyry copper, iron ore and gold deposits you see on other doors. It’s a reminder that not all mines are about metals; some of the most visually striking open pits globally are actually extracting minerals for paper, plastics, paints and cosmetics.

What the mining satellite timelapse shows

The mining satellite timelapse for Trimouns (1984–2022) compresses nearly four decades of quarry development into a short clip. It gives a visual snapshot of how a long-lived industrial minerals operation evolves on a steep mountain slope – and why the pit often appears almost snow-white from space, as talc and talc-rich waste rocks are very pale, white materials.

1. 1980s – a smaller amphitheatre in the mountain

• By the mid-1980s, Trimouns had already been in production for decades, but the open pit footprint was still relatively compact by today’s standards.
• Annual production at that time was far below current levels; historical sources suggest that early Trimouns production was on the order of tens of thousands of tonnes per year, rising progressively during the 20th century.

What you see from space:

• • A bright, bowl-shaped quarry carved into the hillside.
  • Early benches visible as narrow terraces.
  • Initial waste tips and access tracks developing below the pit.

2. 1990s – widening benches and higher output

• Through the 1990s, Trimouns’ role as a major European talc source is firmly established, with further benching and pushbacks to access additional talc–chlorite zones.
• Processing capacity at Luzenac is modernised; the quarry gradually transitions to more mechanised, high-productivity mining practices.

In the timelapse:

• The open pit widens laterally, creating a larger amphitheatre with more continuous benches.
• Waste dumps become more structured, with clearly defined tipping areas and access roads.
• The bench pattern becomes a key “signature” for MineGuessr players trying to identify the site.

3. 2000s – world-class talc quarry and optimisation

• By the early 2000s, Trimouns is recognised as one of the largest open-pit talc mines globally, with annual output rising toward the ~400,000 t/year level cited in technical and industry references.
• Work such as drill-and-blast optimisation and overburden haulage projects further refines how the quarry is mined and how material is moved.

In the timelapse:

• The pit grows to an ~800 m-wide amphitheatre with multiple working levels across the face.
• Bench geometry appears more regular and the main haul road system stabilises.
• Waste dumps expand but also show signs of re-profiling and partial revegetation on older faces.

4. 2010s–2020s – mature footprint and low-carbon logistics

• Trimouns continues to produce around 400,000 t of talc per year, employing over 300 permanent workers plus seasonal staff.
• Imerys emphasizes sustainability: the talc ore is transported down to Luzenac via a 5.5 km cableway, removing a significant number of truck journeys from the mountain road and cutting emissions.
• Guided quarry visits operate in season, turning Trimouns into both an industrial site and a geotourism and STEM-education destination.

From a MineGuessr lens: the recent frames show a mature quarry with a fairly stable final outline, incremental deepening, and ongoing waste-dump shaping rather than dramatic lateral expansion. It’s an excellent visual example of how a long-life industrial minerals deposit reaches a steady-state footprint while continuing to supply global markets.

Mining method & processing – how the talc moves

Trimouns is a mechanised open-pit truck-shovel quarry with valley-floor processing:

• Drill & blast: Overburden and talc-bearing rock are drilled and blasted along the bench faces.
• Loading & haulage: Wheel loaders and truck fleets move ore and waste within the pit and to nearby dumps and primary crushing facilities.
• Cableway transport: Crushed ore is moved down the mountain on a dedicated cableway to the Luzenac processing plant.
• Processing: At Luzenac, the ore is milled, beneficiated and classified into a wide range of talc products tailored for different industrial applications.

The mine and plant together form one of the most important integrated talc operations in Europe.

Role in the raw materials value chain and energy transition

Unlike the copper, iron or gold mines elsewhere in the MineGuessr calendar, Trimouns sits firmly in the industrial minerals value chain. Talc from Luzenac feeds into:

• Paper and board: As a filler and coating pigment to improve printability, smoothness and barrier properties.
• Plastics and rubber: To increase stiffness, impact resistance and dimensional stability in automotive parts, packaging and consumer goods – highly relevant when we talk about lightweighting for electric vehicles and more efficient logistics.
• Paints, coatings and ceramics: For improved rheology, durability and surface finish.
• Cosmetics, pharmaceuticals and food: Where talc’s chemical inertness and softness are critical.

So while talc is not a “battery metal”, the Trimouns story is still tightly linked to the energy transition: lighter vehicles, improved packaging performance, and the need for low-carbon, responsibly produced functional minerals.

What to look for in the MineGuessr timelapse

As a MineGuessr player, see if you can spot:

1. The growth of the amphitheatre-shaped pit as additional benches are cut higher and wider into the hillside.
2. Progressive re-profiling and partial revegetation of older waste dumps as the quarry footprint matures.
3. The strong contrast between the bright, almost snow-white talc benches (talc is a very light, white mineral) and the darker, vegetated surroundings – a tell-tale clue compared with metal mines in more subdued colour palettes.
4. The relatively compact but very steep footprint compared with the giant, low-slope open pits elsewhere in the MineGuessr calendar.

MineGuessr perspective – why this mine was included

We selected Trimouns for the MineGuessr mining advent calendar because it:

• Is a world-class industrial minerals operation, representing talc in a calendar otherwise dominated by metals.
• Shows a clear life-of-quarry evolution in the satellite timelapse – from a smaller amphitheatre to a large, multi-bench open pit with a stable mature outline.
• Illustrates the high-altitude, seasonal operating model and low-carbon logistics (cableway) typical of modern European industrial mineral sites.

In our GeoGuessr-style mine guessing game, Trimouns helps spark conversation about talc deposits, industrial minerals, and how “non-metal” mines still play a central role in global supply chains.

In December, keep opening a new door every day and explore all 24 mines featured this year on the main MineGuessr mining advent calendar page.

• Day 1 - Aitik (Sweden, copper-gold open pit)
  A large, low-grade copper operation south of Gällivare
  👉 Open Door 1 - Aitik
• Day 2 - Björkdal (Sweden, gold)
  Gold mine near Skellefteå, combining open-pit and underground mining.
  👉 Open Door 2 - Björkdal
• Day 3 - Kemi (Finland, chrome)
  Chrome mine in northern Finland, Europe’s only chromite operation.
  👉 Open Door 3 - Kemi
• Day 4 - Ørtfjell (Norway, iron ore)
  Iron ore mine in Norway’s Dunderland Valley, evolving from large open pits to underground mining.
  👉 Open Door 4 - Ørtfjell
• Day 6 - Skouries (Greece, copper-gold porphyry)
  High-grade copper–gold porphyry project in the forests of Halkidiki, still under construction.
  👉 Open Door 6 - Skouries
• Day 7 - Las Cruces (Spain, copper)
  High-grade hydromet copper mine in the Iberian Pyrite Belt north-west of Seville.
  👉 Open Door 7 - Las Cruces
• Day 8 - Assarel–Medet (Bulgaria, copper)
  Twin porphyry copper open pits in the Panagyurishte district, from Europe’s former largest open-pit copper mine at Medet to today’s modern Assarel operation.
  👉 Open Door 8 - Assarel–Medet
• Day 9 - Glomel (France, andalusite)
  World-class andalusite open-pit quarry in Brittany’s Montagnes Noires, supplying refractory minerals for Europe’s steel, foundry, cement and glass industries.
  👉 Open Door 9 - Glomel
• Day 10 - Parnassos–Ghiona (Greece, bauxite)
  Karst-type bauxite mines in the Parnassos–Ghiona mountains, a historic alumina feedstock district supplying Greece’s aluminium industry.
  👉 Open Door 10 - Parnassos–Ghiona
• Day 11 - Kittilä (Finland, gold)
  Europe’s largest primary gold mine at the Suurikuusikko orogenic gold deposit north of the Arctic Circle.
  👉 Open Door 11 - Kittilä
• Day 12 - Oltenia Energy Complex (Romania, lignite)
  Cluster of large open-pit lignite mines and mine-mouth power plants in Gorj County, now at the centre of Romania’s coal phase-out and just transition plans.
  👉 Open Door 12 - Oltenia Energy Complex
• Day 13 - Cornwall china clay (UK)
  Historic Imerys china clay pits near St Austell, where bright white kaolin benches and tips reshape “Clay Country” over decades of mining and restoration.
  👉 Open Door 13 - Cornwall china clay

---

About Gosselin Mining

At Gosselin Mining, we work not only with metal mines but also with industrial mineral operations like Trimouns: long-life quarries where value comes from geology, selective mining, product quality and logistics optimisation. If you need help to:

• Stress-test your life-of-quarry plan and selective mining strategy
• Benchmark industrial mineral logistics and decarbonisation options (rail, cableway, electrified haulage)
• Position your project within the broader raw materials value chain and ESG expectations

…you’re very welcome to book a meeting with us.

Further Reading and References

1. Imerys (online). Talc. Available at: https://www.imerys.com/minerals/talc (Accessed 5 December 2025).
2. Wikipedia (online). Carrière de talc de Trimouns. Available at: https://fr.wikipedia.org/wiki/Carri%C3%A8re_de_talc_de_Trimouns (Accessed 5 December 2025).
3. Ariège.com (online). Trimouns: the largest talc quarry in the world. Available at: https://www.ariege.com/en/discover-ariege/geology/trimouns-talc-quarry (Accessed 5 December 2025).