Architectural masters of minerals
The world of silicates is a large, very comprehensive world. What carbon is for organics, silicon is for inorganics. 60 % of the earth's crust consists of SiO₂. Al₂O₃ is found in 15% of the earth's crust. We are primarily concerned here with the phyllosilicates.
Layer silicates
Layered silicates consist of [Si₂O₅²⁻]x silicate layers in which the oxygen atoms of the two-dimensionally-infinitely linked SiO₄ tetrahedra are uniformly aligned to one side. These layers slide under mechanical influence. As a result, a layered silicate has only gentle polishing properties.
Kaolinite
P15-NA corresponds to the mineral kaolinite, a phyllosilicate that occurs naturally. The name kaolinite is derived from the rock kaolin, of which it is the main component.
Kaolin in turn is derived from the first place of discovery, the Chinese village of Gaoling (from Chinese: gāo lĭng = high hill). Kaolinite has a Mohs' hardness of 2 to 2.5, a density of 2.61 to 2.68 g/cm³. In water, kaolin becomes plastically deformable. The mineral is ubiquitous as an aluminium silicate in the soils of warm, humid regions and can be found all over the world.
It was used as a filler mineral in paper production as early as 105. 600 years later, it was then used as a raw material in the Chinese ceramics and porcelain industry near the hill mentioned above. It is also used in the rubber, paint and plastics industries, as a filler and carrier for medicines, etc., and as an adsorbent. It is purified and calcined before being used in industry.