Kaolinite Facts for Kids

Quick facts for kids Kaolinite

General
Category	Phyllosilicates Kaolinite-serpentine group
Formula (repeating unit)	Al₂Si₂O₅(OH)₄
Strunz classification	09.ED.05
Crystal symmetry	Triclinic pedial H-M symbol: (1) Space group: P1
Unit cell	a = 5.13 Å, b = 8.89 Å, c = 7.25 Å; α = 90°, β = 104.5°, γ = 89.8°; Z = 2
Identification
Color	White, sometimes red, blue or brown tints from impurities
Crystal habit	Rarely as crystals, thin plates or stacked, More commonly as microscopic pseudohexagonal plates and clusters of plates, aggregated into compact, claylike masses
Crystal system	Triclinic
Cleavage	Perfect on {001}
Tenacity	Flexible but inelastic
Mohs scale hardness	2–2.5
Luster	Pearly to dull earthy
Streak	White
Specific gravity	2.16–2.68
Optical properties	Biaxial (–)
Refractive index	n_α = 1.553–1.565, n_β = 1.559–1.569, n_γ = 1.569–1.570
2V angle	Measured: 24° to 50°, Calculated: 44°

Kaolinite (say: KAY-oh-lih-nite), also called Kaolin, is a common clay mineral. It is made of aluminum, silicon, oxygen, and hydrogen atoms. Its chemical formula is Al₂Si₂O₅(OH)₄.

Kaolinite is a type of silicate mineral that forms in layers. Rocks that have a lot of kaolinite are known as kaolin or china clay.

Where does the name Kaolinite come from?
What does Kaolinite look like?
How is Kaolinite used?
Images for kids
See also

Where does the name Kaolinite come from?

The name Kaolinite comes from Kao-Ling. This is a village near Jingdezhen in Jiangxi province, China. The name first came into English in 1727. It came from the French word kaolin. A Jesuit priest used this word in his reports from Jingdezhen. In Africa, kaolin is sometimes called kalaba or calaba.

What does Kaolinite look like?

Kaolinite is usually a soft, earthy, white mineral. It is a type of clay. It forms when other aluminium silicate minerals, like feldspar, break down.

Sometimes, kaolinite can be pink, orange, or red. This happens when it has iron oxide mixed in. Lighter amounts of iron oxide make it white, yellow, or light orange. You can sometimes see different colored layers of kaolinite. For example, this happens at Providence Canyon State Park in Georgia, United States.

How is Kaolinite used?

Kaolinite is very useful in many industries. It does not shrink or swell much, which is a good quality for many products.

One of its main uses is in making porcelain. Today, it is mostly used to make paper, especially shiny, white paper. Kaolinite is also found in toothpastes, make-up, and paint.