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Tectosilicates, or "framework silicates," have a three-dimensional framework of silicate tetrahedra with SiO 2 in a 1:2 ratio. This group comprises nearly 75% of the crust of the Earth. [6] Tectosilicates, with the exception of the quartz group, are aluminosilicates. The Nickel–Strunz classifications are 09.F and 09.G, 04.DA (Quartz/ silica ...
In a framework silicate, known as a tectosilicate, each tetrahedron shares all 4 oxygen atoms with its neighbours, forming a 3D structure. Quartz and feldspars are in this group. Silicates with non-tetrahedral silicon
Tectosilicates are framework silicates which have a three-dimensional framework of silicate tetrahedra with an Si:O ratio of 1:2. This is the largest mineral group comprising nearly 75% of the crust of the Earth.
Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth 's continental crust , behind feldspar .
All silicates have a basic structural unit that is a tetrahedron with an oxygen ion O at each apex, and a silicon ion Si in the middle, forming (SiO 4) 4−. In tectosilicates (framework silicates) each oxygen ion is shared between two tetrahedra, linking all the tetrahedra together to form a framework.
Hsianghualite is a tectosilicate (framework silicate) of lithium, calcium and beryllium, with fluorine, a member of the zeolite group. It was discovered in 1958 and named for the type locality, Hsiang Hua, 香花, meaning fragrant flower.
Kaolinite (/ ˈ k eɪ. ə l ə ˌ n aɪ t,-l ɪ-/ KAY-ə-lə-nyte, -lih-; also called kaolin) [5] [6] [7] is a clay mineral, with the chemical composition Al 2 Si 2 O 5 4.It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO 4) linked through oxygen atoms to one octahedral sheet of alumina (AlO 6).
Framework silicates are also known as tectosilicates. When devitrifying silica, cristobalite is usually the first phase to form, even when well outside its thermodynamic stability range. This is an example of Ostwald's step rule. The dynamically disordered nature of the β phase is partly responsible for the low enthalpy of fusion of silica.