Short answers, pulled from the story.
Kaolinite is a soft, earthy, usually white clay mineral with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral formed by the chemical weathering of aluminium silicate minerals like feldspar. Rocks rich in kaolinite are known as kaolin or china clay.
The English name kaolin was borrowed in 1727 from François Xavier d'Entrecolles's 1712 French reports on the manufacture of Jingdezhen porcelain. It transcribes a Chinese term, now romanized as gaolingtu, taken from the village of Gaoling, meaning High Ridge, near Ehu in Fuliang County. The suffix -ite was later added to generalize the name.
The main United States kaolin deposits are in central Georgia, along the Atlantic Seaboard fall line between Augusta and Macon. This area of thirteen counties is called the white gold belt, and Sandersville is known as the Kaolin Capital of the World. United States kaolin production in 2011 reached 5.5 million tons.
Kaolinite is used in paper, ceramics, and paint, with paper accounting for 36 percent of the market by 2016. It also appears in toothpaste as a mild abrasive, in treatments for diarrhea and upset stomachs, in blood-clotting gauze, and in cosmetics. In whiteware ceramic bodies it can form up to 50 percent of the raw materials.
Heating drives kaolinite through a series of irreversible transformations. Above around 400 degrees Celsius it loses hydroxyl ions in a process called calcination, then forms disordered metakaolin at 550 to 600 degrees. Further heating produces an aluminium-silicon spinel at 925 to 950 degrees, platelet mullite above 1050 degrees, and needle mullite at 1400 degrees.
A kaolinite layer carries no net electrical charge, so no large cations sit between the layers as in most other clay minerals. Close hydrogen bonding between layers also keeps water molecules from infiltrating, giving kaolinite its nonswelling character and a low cation-exchange capacity of 1 to 15 milliequivalents per 100 grams.
Global production of kaolin in 2021 was estimated at 45 million tonnes, with a total market value of US $4.24 billion. It is mined across many countries, including China, Germany, the United States, Brazil, and India.