Kaolin & clays: Characteristics
Sold on what they do: brightness, swelling, strength
What this tab covers The supply and physical characteristics of the commodity. Supply: current production, inventories and stocks, capacity utilisation, geographic and producer concentration, how fast supply responds to price, the project pipeline and capital spending, and logistics and export flows. Material: the physical and chemical properties that set its grade, price and end uses (for example purity and conductivity for metals, API gravity, sulfur and energy content for fuels, moisture, protein and fibre quality for crops).Supply volume characteristics
| Characteristic | Figure | What it means | Source |
|---|---|---|---|
| Current production volume | kaolin about 50 Mt and bentonite about 20 Mt (2025e, USGS); kaolin 48.9 Mt in 2024 (World Mining Data) | Kaolin: India 8.4 Mt (with crude ore), China 7.8 Mt, Uzbekistan 6.0 Mt, Russia 5.0 Mt, US 4.8 Mt. Bentonite: US 4.1 Mt, India 3.7 Mt, Turkey 2.5 Mt. US total clays were 26 Mt, half of it common clay for brick and cement. | USGS MCS 2026; World Mining Data 2026 |
| Inventory and stock levels | not published; no exchange or strategic stocks | Stocks are pit and plant stockpiles; processed kaolin is held as slurry or dry product at plants and ports. No government stockpile. | USGS MCS 2026 |
| Capacity utilisation | not published | Ashapura Minechem has 770,000 t a year of bentonite grinding capacity and 108,000 t a year of kaolin capacity in India (Aug 2025), but no utilisation. Paper-coating kaolin plants have run below past peaks as paper demand falls. | Ashapura investor note, Aug 2025; content_v2 |
| Geographic and producer concentration | Kaolin: India about 17%, top-3 about 45%, HHI about 900 (USGS 2025); WMD HHI 1,009 kaolin, 1,243 bentonite (2024) | Country supply is fragmented. Processed paper and coating kaolin is concentrated in a few firms (Imerys, KaMin, Thiele Kaolin, Sibelco), mostly in Georgia (US), Brazil and Cornwall (UK). Company shares not published. | USGS MCS 2026; World Mining Data 2026 |
| Supply elasticity | high for common clay and crude kaolin; moderate for processed kaolin (2-4 years for new refining plants) | Resources are extremely large (USGS). The constraint for premium grades is deposit quality (brightness, particle size) and refining capacity. | USGS MCS 2026 |
| Project pipeline and CapEx | not published | Calcined clay for low-carbon cement (LC3) is the main new demand driver, with pilot plants in India and Africa. No capacity totals found. | Indicative |
| Logistics and export flows | US exported 1.6 Mt of kaolin and 640,000 t of bentonite in 2025; most clay is used near the pit | Only processed grades cross oceans: Brazilian kaolin to the US (imports fell from 176,000 t in 2024 to 19,000 t in 2025), Georgia kaolin to Mexico, Japan and China. Indian ball clay and kaolin exports rose sharply in 2022-23. Common clay worth about $21/t cannot bear long freight. | USGS MCS 2026; IBM 2023 |
Material characteristics Industrial mineral
Clays are fine-grained aluminosilicates whose value depends on what they do in a process. Kaolin is sold on brightness, particle size and viscosity for paper, paint and ceramics. Bentonite is sold on swelling and gel strength for drilling mud, litter and foundry. Ball clay is sold on plasticity and fired strength. Calcined kaolin is now valued for pozzolanic reactivity in low-carbon cement.
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Brightness (kaolin) | Paper-coating grades about 88-92% ISO brightness (indicative) | Sets paper and paint whiteness and price tier | Producer specifications (indicative) |
| Particle size (kaolin) | Coating grades about 80-95% finer than 2 microns (indicative) | Fine plates give gloss and coverage on coated paper | Producer specifications (indicative) |
| Iron and titanium oxides | Fe2O3 under about 1% and low TiO2 for white ceramics (indicative) | Colour of fired porcelain and sanitaryware | Industry specifications (indicative) |
| Swelling and rheology (bentonite) | API Spec 13A: viscometer dial reading at 600 rpm at least 30, yield point to plastic viscosity ratio at most 3, filtrate volume at most 15 ml, residue over 75 microns at most 4% | Qualifies bentonite as drilling mud | API Spec 13A |
| Kaolinite content for calcined clay | Clays with at least about 40% kaolinite give good LC3 cement performance | Sets reactivity when calcined at about 700-850 C | Scrivener et al. 2018, Cement and Concrete Research (indicative) |
| Plasticity and fired strength (ball clay) | High plasticity and green strength; modulus of rupture varies by grade | Lets tiles and sanitaryware be shaped and handled before firing | Industry practice (indicative) |