Kaolinite
A widely used clay mineral in porcelain and industry.
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Kaolinite is a clay mineral with the chemical composition Al2Si2O5(OH)4, also known as kaolin or china clay. It is a soft, earthy, usually white, layered silicate mineral produced by the chemical weathering of aluminium silicate minerals like feldspar, and is an important raw material in many industries.
Lore & Background
D'Entrecolles was transcribing the Chinese term 高嶺土, now romanized as gāolǐngtǔ, taken from the name of the village of Gaoling near Ehu in Fuliang County, now part of Jiangxi Province's Jingdezhen Prefecture. The mineralogical suffix -ite was later added to generalize the name. Kaolinite is also occasionally discussed under the archaic name lithomarge, though 'lithomarga' is not a standard variant.
Reader's Guide
Kaolinite is significant as a key raw material in ceramics, paper, paint, and many other industries. Its structure—a 1:1 or TO clay mineral with stacked tetrahedral and octahedral sheets—gives it low shrink–swell capacity and low cation-exchange capacity, making it valuable for applications requiring stability.
The mineral undergoes phase transformations upon heating, producing metakaolin, spinel, and mullite phases, which are important in high-temperature ceramics. Major deposits occur in the United States (especially central Georgia), as well as in Australia, Brazil, China, and many other countries. Kaolinite-rich soils, called kaolisol in the INERA classification system, are common in tropical regions and are used to infer past climates.
Did You Know?
- Kaolinite has a low cation-exchange capacity of 1–15 meq/100 g.
- Kaolinite is not among the most abundant minerals in the Earth's crust—feldspars, quartz, and micas are far more common.
Frequently Asked Questions
What is Kaolinite in the Geology & Earth Science series?
Kaolinite is a soft, layered silicate clay mineral with the chemical formula Al₂Si₂O₅(OH)₄, also referred to as kaolin or china clay. It is one of the most recognizable clay minerals and is typically found in a pale, earthy-white form.
How does Kaolinite form in nature?
Kaolinite develops through the chemical weathering of aluminium silicate minerals, most commonly feldspar, as water and weak acids gradually break down the parent rock. The process rearranges the atoms into the characteristic stacked-sheet structure that defines the mineral.
What role does Kaolinite play in industry?
Kaolinite is a foundational raw material in porcelain and ceramic manufacturing, and it also appears in paper coating, paint, rubber, and other products. Its soft texture, bright white colour, and chemical inertness make it especially prized for giving finished goods a smooth, opaque surface.
How much Kaolinite is produced worldwide?
Industry estimates place global output at roughly 25 to 30 million tonnes per year as of 2021. A single canonical market-value figure is not consistently reported across authoritative references, so economic valuations vary depending on the source.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Kaolinite (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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