Dissolved from practically all rocks and soils, silica (SiO 2) is generally found in small amounts from 1 ppm to 30 ppm. Higher concentrations generally occur in highly alkaline water. Silicas form a hard scale in pipes and boilers.
It is a soft, white metallic element and alkaline. Barium: Historical data, properties and other information about this element. Bauxite. Bauxite is a sedimentary rock that is an important ore of aluminum. The aluminum content in it is leeched from the soil above. Bauxite : Photos and usage information. Beryllium