Diatomite

Fossil skeletons of microscopic algae, mined as a light, porous silica powder that filters beer, wine, water and oils.

Industrial minerals · No. 67

• Not on a critical list
• HHI 1,676 · moderately concentrated

Your beer, wine and tap water may be filtered through the fossil skeletons of microscopic algae dug from ancient lake beds.

Chart: Illustration: Diatomite

Where it comes from

Chart: Map of where it comes from

Diatomite is the piled-up silica shells of dead diatoms, laid down in ancient lakes and seas. US deposits in California, Nevada, Oregon and Washington lie near the surface, so open pits are cheap.

Three things to know

1. About 60% of US diatomite goes into filtration, including beer, wine and public drinking water.
2. In 2025 diatomite sold for about $10/t as concrete aggregate but over $1,000/t for DNA extraction and cosmetics.
3. Diatomite is also called kieselguhr, and an impure Danish form is moler; Denmark supplied about 15% of world output in 2025.

The journey

1. 1 SedimentDiatom-rich ancient lake or sea beds
2. 2 MiningOpen pit or underground
3. 3 ProcessingDried, milled and air-classified
4. 4 CalciningHeated or flux-calcined for filter grades
5. 5 End usesFilter aids, absorbents, fillers, pesticide carriers

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