Kaolinite
Aluminum
Silicate Hydroxide
Al2Si2O5(OH)4
Kaolinite shares the same chemistry as the minerals halloysite,
dickite and nacrite.
The History Says
Kaolinite is also known as china clay and kaolin, named after Gaoling
("High Hill") in Jingde Town, Jiangxi, China. It was
Discovered in the year 1867 in Kao-Ling, China.
The Present Scenario
Kaolinite is important to the production of ceramics and porcelain,
and to produce glossy paper for magazines.
Kaolinite
is a common phyllosilicate mineral. It is named for its type locality,
Kao-Ling, Jianxi, China. It forms Kaolinite Group, members of which
even belong to larger general group, Clays. Kaolinite's structure is
composed of silicate sheets (Si2O5) bonded to
gibbsite layers, aluminum oxide/hydroxide layers, Al2(OH)4.
Natural Kaolinite usually contains small amounts of uranium and
thorium. Hence, it is useful in radiological dating. The
crystallography of Kaolinite played an important role in Linus
Pauling's work on the nature of the chemical bond.
Physical Properties of Kaolinite
| Color |
Usually white,
colorless, greenish or yellow. |
| Luster |
Earthy |
| Transparency |
Crystals are translucent. |
| Crystal system |
Triclinic; 1. |
| Crystal habits |
Foliated and earthy masses.
Crystals of any size are rare and is usually microscopic. |
| Cleavage |
Perfect in one direction,
basal. |
| Fracture |
Earthy |
| Hardness |
1.5-2 (can leave marks on
paper). |
| Specific gravity |
2.6 (average). |
| Streak |
White |
| Other characteristics |
Clay like properties when water
is added. |
Associated Minerals of Kaolinite
- Fluorite
- Microcline
- Pyrite
- Hemimorphite
- Augite
- Dickite
- Halloysite
- Montmorillonite
- Quartz
- Muscovite
- Other
clays
Occurrences of Kaolinite
Kaolinite
is spread around the world. Few of the localities are as follows:
- Kao-Ling,
Jianxi (China)
- Cornwall
and Devon (England)
- Haute-Vienne
(France)
- Near
Dresden, Saxony (Germany)
- Donets
Basin (Ukraine)
- Huberdeau,
Quebec, and near Walton, Nova Scotia (Canada)
- Macon,
Georgia (United States)
- Dixie
Clay Company Mine (South Carolina)
- Near
Webster (North Carolina)
- Arkansas
- Mesa
Alta (New Mexico)
- Sterling
Hill (New Jersey)
Uses of Kaolinite
- In
the production of ceramics.
- As
a filler for paint, rubber and plastics.
- In
paper industry, to produce glossy paper as used in most magazines.
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