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Kaolinite |
  
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Kaolinite |
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Kaolinite, which is named for its type locality, Kao-Ling, Jianxi, China; is a common phyllosilicate mineral. It lends it name to the Kaolinite Group, members of which also belong to the larger general group known as the Clays.
Kaolinite's structure is composed of silicate sheets (Si2O5) bonded to aluminum oxide/hydroxide layers (Al2(OH)4) called gibbsite layers. Kaolinite shares the same chemistry as the minerals halloysite, dickite and nacrite. The four minerals are polymorphs. All four minerals form from the alteration (mostly weathering) of aluminum rich silicate minerals such as feldspars. Kaolinite is by far the most common and most clay deposits contain at least some kaolinite. In fact, clay deposits will frequently be nearly 100% kaolinite pure!
Kaolinite is important to the production of ceramics and porcelain. It is also used as a filler for paint, rubber and plastics since it is relatively inert and is long lasting. But the greatest demand for kaolinite is in the paper industry to produce a glossy paper such as is used in most magazines.
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