sedimentary

Kaolin Clay in Saprolite Profile

Kaolinite (Al2Si2O5(OH)4) within Weathered Pegmatite/Granite

AI-generated identification · may be incorrect

Hardness: 2-2.5 (Mohs); Color: White, cream, or iron-stained reddish-brown; Luster: Dull, earthy; Crystal structure: Triclinic (microscopic plates); Cleavage: Perfect; Specific gravity: 2.6

Hardness: 2-2
Color: White, cream, or iron-stained reddish-brown
Luster: Dull, earthy

Identified June 20, 2026More sedimentary →

Explore Kaolin Clay in Saprolite Profile in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 2-2.5 (Mohs); Color: White, cream, or iron-stained reddish-brown; Luster: Dull, earthy; Crystal structure: Triclinic (microscopic plates); Cleavage: Perfect; Specific gravity: 2.6

Formation & geological history

Formed through the hydrothermal alteration or intense chemical weathering (kaolinization) of feldspar-rich rocks like granite and pegmatite. This outcrop represents a saprolite profile, typically found in tropical environments.

Uses & applications

Used extensively in the paper industry for coating, ceramics, porcelain, toothpaste, cosmetics, and as a filler in rubber and plastics.

Geological facts

Kaolin is also known as China Clay. It is essential for making fine porcelain (fine china). Massive deposits like this often indicate deep tropical weathering over millions of years.

Field identification & locations

Identify in the field by its soft, chalky feel, white to light gray color when pure, and the fact that it stays on your hands like flour when dry and becomes plastic/sticky when wet. Common in West Africa, SE USA, and Brazil.