Kaolinite (inclusions in Quartz)
Current inventory: 0 gems
 

  
Kaolinite was named in 1637 by Chinese scientist and encyclopedist Song Yingxing (1587-1666) for the ancient Chinese type locality at the "Kao-Ling" Mine (from Gaoling, meaning high ridge), Jingdezhen Prefecture, Jiangxi Province, China.

Discovered in ancient times; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Al₂Si₂O₅(OH)₄

Aluminum Silicate Hydroxide

Molecular Weight:

258.16 gm

Composition:

Aluminium

20.90 %

Al

39.50 %

Al₂O₃

Silicon

21.76 %

Si

46.55 %

SiO₂

Hydrogen

1.56 %

H

13.96 %

H₂O

Oxygen

55.78 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/H.25-10

Nickel-Strunz 10th Ed. ID:

9.ED.05

9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets

Related to:

Kaolinite-Serpentine Group. Dickite, Halloysite and Nacrite are polymorphs. Chemically identical to Halloysite-7Å.

Members of Group:

Kaolinite-Serpentine Group: Amesite, Antigorite, Baumite, Berthierine, Brindleyite, Caryopilite, Chrysotile, Clinochrysotile, Cronstedtite, Dickite, Fraipontite, Greenalite, Halloysite, Kaolinite, Kellyite, Lizardite, Manandonite, Nacrite, Népouite, Odinite, Orthochrysotile, Parachrysotile, Pecoraite, Webskyite 

Varieties:

Chrome-Kaolinite, Keramite (of Hunt), Parakaolinite

Synonyms:

Ancudite, Carnat, China Clay, Clayite (of Mellor), Cleîte, Collyrinum, Collyrum, Creniadite, Fireclay, Kaolin, Leucargilla, Marga Porcellana, Myelin, Neokaolin, Pholerite, Porcelain Clay, Porcelain Earth

Crystal Data

Crystallography:

Triclinic - Pedial

Crystal Habit:

Rarely as crystals, thin platy or stacked, to 2 mm. More commonly as microscopic pseudohexagonal plates and clusters of plates, aggregated into compact, claylike masses. 

Twinning:

None

Physical Properties

Cleavage:

Perfect on {001}

Fracture:

Irregular/Uneven, conchoidal, sub-conchoidal, micaceous

Tenacity:

Sectile, flexible but inelastic

Moh's Hardness:

2.0 - 2.5

Density:

2.61 - 2.68 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

White to tan or cream and pale-yellow; also often stained various hues of tans and browns by impurities

Transparency:

Transparent to opaque, translucent as single crystals

Luster:

Waxy, pearly to dull, earthy

Refractive Index:

1.553 - 1.570  Biaxial ( - )

Birefringence:

0.007 - 0.017

Dispersion:

Weak; r > v

Pleochroism:

None

Occurances

Geological Setting:

Replaces other aluminosilicate minerals during hydrothermal alteration and weathering. A common constituent of the clay-size fraction of sediments, where it may be formed by direct precipitation.

Common Associations:

Quartz, Feldspar, Muscovite

Common Impurities:

Fe, Mg, Na, K, Ti, Ca, H₂O

Type Locality:

Gaoling Mine (Kaoling Mine), Gaoling village, Ehu town, Fuliang County, Jingdezhen Prefecture, Jiangxi Province, China

Year Discovered:

Ancient times. Known since the Yuan (Mongol) dynasty in the thirteenth century. Named in 1637

View mineral photos:

Kaolinite Mineral Photos and Locations

Unusual Gem Categories

Inclusions in Quartz

More Information

Mindat.org
Webmineral.com

Kaolinite has been known since at least the Yuan (Mongol) dynasty in the thirteenth century as "Kaolin earth". It is a "clay mineral". Clay minerals are hydrous aluminium phyllosilicates, often with variable amounts of iron, magnesium, alkali metals or alkaline earths. Kaolinite is typically white to cream or pale-yellow or may often be stained various hues of tans and browns by impurities.

Kaolinite was first properly described and named in 1637 by Chinese scientist and encyclopedist Song Yingxing (1587-1666) who lived during the late Ming Dynasty. Kaolinite was named for the ancient Chinese type locality at the "Kao-Ling" Mine (from Gaoling, meaning high ridge), Jingdezhen Prefecture, Jiangxi Province, China. Kaolinite was possibly the most important mineral in clays used in pre-historic pottery. Kaolinite was introduced to the West by a French priest in 1712.

Kaolinite is largely found in masses, in clay beds, usually with a bright white color. Kaolinite is too soft to be used as a gem on its own, but it is available as inclusions in Quartz gems. The picture above shows a faceted Quartz gem with beautiful inclusions of white Kaolinite. If you place your cursor over the picture you will see a magnified picture of white Kaolinite formations in the Quartz. This gem is from a recent find in Madagascar.

Kaolinite distribution: pure material from many localities, including: at Kauling, Kiangsi Province, China. In numerous china-clay pits in Cornwall and Devon, England. At Limoges, Haute-Vienne, France. Near Dresden, Kemmlitz, and Zettlitz, Saxony, and elsewhere in Germany. Large deposits in the Donets Basin, Ukraine. In the USA, at Macon, Bibb County, Georgia; at the Dixie Clay Company mine, and in the Lamar Pit, near Bath, Aikin County, South Carolina; near Webster, Jackson County, North Carolina; near Murfreesboro, Pike County, and at Greenwood, Sebastian County, Arkansas; from Mesa Alta, Rio Arriba County, New Mexico. At Huberdeau, Quebec, and near Walton, Nova Scotia, Canada.
 

  
Kaolinite gems for sale:

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