MineGuessr – Cornwall, UK: Imerys China Clay (Kaolin) Pits

Overview & location

The coordinates used in this MineGuessr door lie within Imerys’ western area of operations in the St Austell china clay district of mid-Cornwall, south-west England. This is part of a wider kaolin field that stretches across roughly 35 square miles of “Clay Country”, where open pits, sand tips and mica dams have been developed continuously since the 18th century.^[1]

Today, Imerys’ UK operations in Cornwall and Devon produce kaolin (china clay) alongside other industrial minerals for a wide range of end-uses – from paper and board to ceramics, paints, plastics, construction products and speciality applications.^[2] The western area near Roche and Littlejohns is one of the company’s key production hubs and the focus of recent investments in dry mining and modern processing to supply more than 500,000 t/year of kaolin from a single plant.^[3]

From a MineGuessr perspective, this “door” does not represent a single named pit, but rather the broader cluster of working and exhausted china clay quarries in the western St Austell district – a patchwork of bright white benches, deep blue water-filled voids, restored heathland and young woodland.

Geology & deposit type

The Cornwall china clay district is a classic example of granite-hosted kaolinisation. Kaolin (china clay) forms where feldspar-rich zones of the Cornubian Batholith – particularly the St Austell granite – have been deeply weathered and hydrothermally altered, transforming feldspars into kaolinite and leaving a residual mixture of clay, mica and quartz.^[4][5]

Key geological features include:

• Kaolinised granite caps – economic deposits are irregular lenses and pockets in the upper parts of the St Austell granite, not tabular seams. Their geometry strongly influences pit design and sequencing.
• Kaolin + mica + quartz assemblage – the product is the fine, bright kaolin fraction, but for every tonne of saleable clay historically mined, up to nine tonnes of waste rock, sand and mica have been generated, explaining the extensive tips visible from space.^[1]
• Hydrothermal and supergene processes – both hot fluids and prolonged weathering contributed to kaolinisation, creating variable thickness, grade and brightness across the field.

In MineGuessr, Cornwall’s china clay pits represent our industrial minerals / “white gold” case study – complementing porphyry copper, talc, bauxite and other deposit types in the advent calendar.

What the mining satellite timelapse shows

The mining satellite timelapse for the UK West Kaolin area (1984–2022) compresses several decades of mine evolution into a few seconds. It offers a visual cross-section through the history of a mature industrial minerals district balancing production, closure and restoration.

1. 1980s–1990s – expansion of the “Cornish Alps”

• By the mid-1980s, Cornwall had already been producing china clay for over two centuries, and the St Austell area was one of the world’s largest kaolin provinces.^[4][5]
• Production volumes were high, with multiple pits and tips operating simultaneously around St Austell, Roche and Nanpean.

What you see from space:

• Existing pits deepen and push back, exposing fresh bright white benches of kaolinised granite.
• Sand and mica tips grow higher and more extensive, forming the distinctive pale ridges that earned the nickname “Cornish Alps”.
• Settling lagoons and process water ponds expand and are rearranged around the pits.

2. 2000s – consolidation, environmental controls and early restoration

• Ownership consolidates under Imerys, and a combination of market pressures and environmental regulation leads to the rationalisation of some older pits and waste areas.^[2][4]
• Greater emphasis is placed on water management and environmental performance – for example, reducing discolouration of local watercourses that historically gave the St Austell River its “White River” name.^[1]

In the timelapse:

• Some pits visibly slow their expansion or transition into water-filled voids.
• Former tips and lagoons begin to show patches of vegetation and more structured landforms.
• New haul roads, pipelines and process facilities appear as the operating footprint is reconfigured.

3. 2010s – large-scale restoration and diversification

• Imerys invests heavily in land rehabilitation and nature recovery, working with local partners to create heathland, woodland and trails on spent clay works in mid-Cornwall.^[2][8][12]
• Some restored pit voids become recreational or landscape assets, and a wider network of restored areas is connected by a ~40 km trail allowing people to explore former mining land.^[12]

In the timelapse:

• Areas that were previously bare white tips gradually turn green and brown as vegetation establishes.
• The contrast between active bright-white pits and restored areas becomes more pronounced.

4. 2020s – dry mining and critical raw materials

• Imerys announces a major investment (≈£18 million) in a new dry mining plant at Littlejohns in the western area, designed to produce >500,000 t/year of kaolin with reduced water use and improved efficiency.^{[3][11][24][27]}
• Through Imerys British Lithium, the company develops a lithium project in an old china clay pit, targeting lithium-bearing mica layers within the same granite system to supply future EV battery demand.^[11][22]

In the most recent frames:

• You can pick out a mix of active pits, restored landscapes, new infrastructure and partially flooded voids, all within a relatively compact district.
• The white scars of historic mining are still visible, but increasingly framed by forestry, heathland and reservoirs.

Mining method & processing – how the clay moves

Cornwall’s china clay pits are large open quarries where kaolinised granite is extracted and processed into high-purity industrial kaolin:

• Mining methods:
  • Historically, many pits relied on hydraulic mining – using high-pressure water monitors to disaggregate soft kaolinised granite into slurry.
  • More recently, operations have increasingly adopted dry mining – truck-and-shovel extraction of kaolinised rock that is then crushed and processed, reducing water usage and enabling more flexible pit design.^[3][17]
• Processing:
  • Crushing, blunging and classification to separate kaolin from quartz sand and mica.
  • Hydrocycloning, bleaching and thickening to achieve target brightness and particle-size distributions.
  • Drying and packaging or slurry shipment to customers around the world.
• Logistics: Historically, china clay has been exported through ports such as Fowey and Par; today, production supports a broad base of UK and international customers in paper, board, ceramics, paints, plastics and speciality products.^[2][4][7]

Role in the raw materials value chain and energy transition

China clay is not a “battery metal”, but it is a critical enabler mineral for many downstream value chains:

• Paper & board: Kaolin is a key pigment and filler in high-quality coated papers and packaging grades, supporting lighter and more resource-efficient products.
• Ceramics: Fine, bright kaolin feeds tile, sanitaryware and technical ceramic sectors across Europe and beyond.
• Paints, plastics and rubber: Kaolin improves whiteness, opacity and rheology, and can reduce reliance on more energy-intensive pigments.

In the context of the energy transition, Cornwall’s china clay district is now part of a broader critical raw materials story. Projects such as Imerys British Lithium seek to co-develop lithium from old clay pits, linking legacy industrial minerals to future battery supply chains.^[11][22] At the same time, land rehabilitation projects and nature recovery partnerships are being used to improve biodiversity, carbon sequestration and landscape resilience on former clay workings.^{[2][8][12][19][32]}

What to look for in the MineGuessr timelapse

As a MineGuessr player, see if you can spot:

1. The growth of white pits and tips during the 1980s–1990s, with benches and waste stacks clearly expanding across the granite plateau.
2. The gradual greening of some tips as restoration and tree planting programmes take hold.
3. The contrast between active bright-white extraction areas and the darker blues and greens of water-filled voids and restored land.
4. Subtle changes in road layouts and plant footprints as dry mining and new processing plants are introduced in the western area.

MineGuessr perspective – why this mine district was included

We selected the Cornwall Imerys china clay pits for the MineGuessr mining advent calendar because they:

• Show an instantly recognisable industrial minerals footprint in satellite imagery – the bright white pits and tips of the “Cornish Alps”.
• Illustrate decades of life-of-mine evolution – from traditional hydraulic mining to modern dry mining and from bare tips to large-scale restoration.
• Highlight how a mature European industrial minerals district can link heritage production, critical raw materials (lithium) and nature recovery in the same landscape.

In our GeoGuessr-style mine guessing game, this door is a chance to talk about kaolin geology, industrial minerals processing, land rehabilitation and co-located critical minerals projects – all visible in a few seconds of satellite timelapse.

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 5 - Trimouns (France, talc)
  World’s largest working talc quarry high in the French Pyrenees above Luzenac.
  👉 Open Door 5 - Trimouns
• 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 14 - Aggeria–Agia Irini (Greece, bentonite)
  Overlapping bentonite open pits on the volcanic island of Milos, anchoring one of Europe’s key industrial minerals districts.
  👉 Open Door 14 - Aggeria–Agia Irini
• Day 15 - Skouriotissa (Cyprus, copper & hydromet)
  Ancient copper mining district in the Troodos ophiolite, now a hydrometallurgical hub processing copper, gold and battery-metal feed.
  👉 Open Door 15 - Skouriotissa
• Day 16 - Tunstead (UK, limestone & cement)
  The UK’s largest limestone quarry near Buxton, feeding an integrated lime and cement works with long-term restoration and biodiversity plans.
  👉 Open Door 16 - Tunstead
• Day 17 - Narva (Estonia, oil shale)
  Large open-pit oil shale mine in Ida-Viru County, supplying the Narva power plants and reshaping the landscape with strip mining and reclamation.
  👉 Open Door 17 - Narva
• Day 18 - Sydvaranger (Norway, iron ore)
  Arctic banded iron formation at Bjørnevatn near Kirkenes, evolving toward DR-grade magnetite for Europe’s green steel transition.
  👉 Open Door 18 - Sydvaranger
• Day 19 - Kevitsa (Finland, nickel–copper–PGE)
  Multimetal open-pit mine in Finnish Lapland, combining Ni–Cu–PGE production with trolley-assisted haulage for lower-emission mining.
  👉 Open Door 19 - Kevitsa
• Day 20 - Styrian Erzberg (Austria, iron ore)
  Terraced “pyramid” open-pit iron ore mine at Eisenerz, turning 12 Mt of rock into ~3 Mt of ore each year for Austria’s steel industry.
  👉 Open Door 20 - Styrian Erzberg
• Day 21 - Minas de Alquife (Spain, iron ore)
  Europe’s largest open-pit iron ore mine in Granada, restarting in 2020 after two decades of closure to supply high-grade ore to European steelmakers.
  👉 Open Door 21 - Minas de Alquife
• Day 22 - Siilinjärvi (Finland, phosphate)
  EU’s only operating phosphate mine in central Finland, mining an Archean carbonatite for fertiliser-grade apatite and creating distinctive pale tailings and phosphogypsum stacks.
  👉 Open Door 22 - Siilinjärvi
• Day 23 - Tellnes (Norway, ilmenite/titanium)
  World-class ilmenite open pit in the Rogaland Anorthosite Province, supplying TiO₂ pigment feedstock from one of Europe’s largest titanium deposits.
  👉 Open Door 23 - Tellnes
• Day 24 - Elatsite (Bulgaria, copper–gold porphyry)
  High-altitude porphyry copper–gold open pit in Bulgaria’s Srednogorie zone, with ore conveyed under the Balkan Mountains to a separate flotation–tailings complex.
  👉 Open Door 24 - Elatsite

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About Gosselin Mining

Gosselin Mining is an independent geology and mining engineering consultancy based in Sweden, working with clients across the Nordics, Europe and globally. We specialise in long-life, large-scale deposits – from porphyry copper and orogenic gold to industrial minerals, iron ore and coal – and in turning complex technical data into bankable, ESG-aware raw-materials strategies.

The MineGuessr series reflects the same focus: understanding how mines evolve over decades, how satellite timelapse links to cut-off decisions, tailings and waste strategies, and how all of this connects to the energy transition.

• Life-of-mine and pit/underground planning, including cut-off optimisation and pushback design
• Independent technical and ESG reviews for investors, lenders and project owners
• Decarbonisation, electrification and tailings/water strategies for existing operations

If you’d like to benchmark your project against operations featured in MineGuessr or stress-test your own life-of-mine plan, you’re very welcome to book a meeting with us.

Further Reading and References

1. Imerys (online) Imerys in Cornwall. Available at https://www.imerys.com/united-kingdom/cornwall (Accessed on 13 December 2025).
2. Environment Agency (online) A whiter smile, a greener environment: cleaning up with China clay. Available at https://environmentagency.blog.gov.uk/2014/04/25/a-whiter-smile-a-greener-environment-cleaning-up-with-china-clay/ (Accessed on 13 December 2025).
3. Wilson, I.R. (2003) Current world status of kaolin from south-west England. Geoscience in South-West England, 10, 417–423. PDF available via the Ussher Society at https://ussher.org.uk/wp-content/uploads/journal/2003/06-Wilson_2003.pdf (Accessed on 13 December 2025).