Kaolinite

Kaolinite properties at a glance

Geology & background

Kaolinite forms by the chemical weathering and hydrothermal alteration of aluminum-rich silicate minerals such as feldspar, producing soft white clay deposits.

Kaolinite enabled the development of true porcelain in China and later in Europe, and it remains a vital industrial mineral for ceramics, paper, and many everyday products.

How to identify Kaolinite

• Look for a soft, white to cream earthy mineral that feels powdery and may stick slightly to the tongue.
• Kaolinite often gives off an earthy clay smell when breathed on or dampened.
• Distinguish it from talc by its earthy rather than soapy feel and from chalk by its lack of reaction to acid.

Where Kaolinite is found

Kaolinite occurs in weathered and hydrothermally altered feldspar-rich rocks worldwide, with notable deposits in the United States, the United Kingdom, China, Brazil, and Germany.

How much is Kaolinite worth?

Value depends on purity, color, size, locality, aesthetics, condition, and provenance.

Common uses

• Porcelain and ceramics
• Paper coating and filler
• Cosmetics
• Rubber and paint filler
• Collector specimens

Interesting facts

• The name kaolin comes from Gaoling, a hill in Jiangxi, China, that was a historic source of the clay.
• Kaolinite is the essential ingredient of porcelain and fine china.
• It is widely used as a coating and filler that gives paper its smooth, bright surface.
• Kaolinite has long been used in medicine and cosmetics as a mild absorbent.

Care & safety

Kaolinite is very soft and crumbly, and masses can powder or break apart with handling.

Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.

Related rocks & minerals

Quartz Quartz Family Feldspar Feldspar Group Muscovite Minerals Jadeite Silicate Minerals Lazurite Silicate Minerals Leucite Silicate Minerals