sedimentary

Kaolinite-rich claystone (kaolin)

Kaolinite, Al₂Si₂O₅(OH)₄, likely in a clay-rich rock

AI-generated identification · may be incorrect

Pale cream to white with reddish iron-oxide staining; dull, earthy luster and fine-grained, layered or flaky texture. Kaolinite has Mohs hardness about 2–2.5 and a platy monoclinic crystal structure; the specimen’s exact composition cannot be confirmed visually.

Identified September 28, 2026More sedimentary →

Explore Kaolinite-rich claystone (kaolin) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Kaolinite commonly forms when feldspar-rich rocks chemically weather or undergo hydrothermal alteration; clay deposits range widely in geological age and may later become compacted into claystone.

Uses & applications

Kaolin is used in ceramics, paper coating, paints, cosmetics, and pharmaceuticals; attractive pieces may be kept as mineral or geological specimens.

Geological facts

Iron oxides can produce the reddish patches seen here, while kaolinite itself is typically white or cream.

Field identification & locations

The soft, pale, earthy material and flaky appearance are consistent with kaolin-rich clay, but a scratch or streak test and mineral analysis would be needed for confident identification. Kaolin deposits occur worldwide, especially in weathered granitic terrains.