Kaolin

« Back to Glossary Index

Kaolin is a particular kind of clay, actually a naturally occurring hydrous aluminum silicate. Most of us associate clay with a murky blackish-green color, but this one is actually a light, white powder (i.e., a very fine natural clay originally from Mt. Kaolin in China, hence the name). It is so light that you will find it in many cosmetic products, where it is used to give more opacity and whiteness.

This type of clay has great absorbing properties, like the more active bentonite, but it is less drying and less aggressive which makes it ideal for those who have dry and sensitive skin.

Kaolin (Wikipedia)

Kaolinite (/ˈk.ələˌnt, -lɪ-/ KAY-ə-lə-nyte, -⁠lih-) is a clay mineral, with the chemical composition Al2Si2O5(OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6) octahedra. Rocks that are rich in kaolinite are known as kaolin (/ˈk.əlɪn/) or china clay. Kaolin is occasionally referred to by the antiquated term lithomarge, from the Ancient Greek litho- and Latin marga, meaning 'stone of marl'. Presently the name lithomarge can refer to a compacted, massive form of kaolin.

Kaolinite
Kaolinite from Twiggs County in Georgia in USA.jpg
General
CategoryPhyllosilicates
Kaolinite-serpentine group
Formula
(repeating unit)
Al2(OH)4Si2O5
IMA symbolKln
Strunz classification9.ED.05
Crystal systemTriclinic
Crystal classPedial (1)
(same H-M symbol)
Space groupP1
Unit cella = 5.13 Å, b = 8.89 Å
c = 7.25 Å; α = 90°
β = 104.5°, γ = 89.8°; Z = 2
Identification
ColorWhite to cream, sometimes red, blue or brown tints from impurities and pale-yellow; also often stained various hues, tans and browns being common.
Crystal habitRarely as crystals, thin plates or stacked. More commonly as microscopic pseudohexagonal plates and clusters of plates, aggregated into compact, claylike masses
CleavagePerfect on {001}
TenacityFlexible but inelastic
Mohs scale hardness2–2.5
LusterPearly to dull earthy
StreakWhite
Specific gravity2.16–2.68
Optical propertiesBiaxial (–)
Refractive indexnα = 1.553–1.565,
nβ = 1.559–1.569,
nγ = 1.569–1.570
2V angleMeasured: 24° to 50°, Calculated: 44°
References
Kaolinite
Traditional Chinese高嶺石
Simplified Chinese高岭石
Literal meaning"Gaoling stone"

The name kaolin is derived from Gaoling (Chinese: 高嶺; pinyin: Gāolǐng; lit. 'High Ridge'), a Chinese village near Jingdezhen in southeastern China's Jiangxi Province. The name entered English in 1727 from the French version of the word: kaolin, following François Xavier d'Entrecolles's reports on the making of Jingdezhen porcelain.

Kaolinite has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g). It is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world it is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lower concentrations yield white, yellow, or light orange colors. Alternating layers are sometimes found, as at Providence Canyon State Park in Georgia, United States. Commercial grades of kaolin are supplied and transported as dry powder, chips, or liquid slurry.

Synonyms:
Kaolin Clay
« Back to Glossary Index

Get to Know Reviva Labs - The Natural Skin Care Authority®

Trusted For Generations

It’s a great feeling to know Reviva is being “handed down” from mother to daughter – and even to their granddaughters. And for our next generation of loyal Reviva users we promise to keep delivering the natural skin care people respect and trust.

Learn More

Natural Skin Care For All

Because of our commitment to the safe, effective ingredients and formulations, most of our products are suitable for all skin types. And if a particular formula is not advisable for all skin types, we'll say so on the packaging.

Learn More

Virtual Consultation

Book your complimentary (free) 15-minute virtual skincare consultation (via Zoom), and one of our consultants will answer your questions and help you to customize a helpful Reviva skin care routine.

Read More

Cruelty Free Skin Care

Reviva Labs is committed to being cruelty-free and has been since our beginning. We’ve never tested on animals, and we’ve remained focused on sourcing our ingredients and all components of our products from like-minded companies.

Learn More