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Biogenic silica (bSi), also referred to as opal, biogenic opal, or amorphous opaline silica, forms one of the most widespread biogenic minerals. For example, microscopic particles of silica called phytoliths can be found in grasses and other plants. Silica is an amorphous metalloid oxide formed by complex inorganic polymerization processes.
Phytoliths (from Greek, "plant stone") are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different intracellular and extracellular structures of the plant. Phytoliths come in varying shapes and ...
Silica cycle. Silicon cycle and balance in the modern world ocean [1] Input, output, and biological silicon fluxes, with possible balance. Total silicon inputs = total silicon outputs = 15.6 Tmol Si yr −1 in reasonable agreement with the individual range of each flux. White arrows represent fluxes of net sources of dissolved silicic acid and ...
Precipitated silica. Precipitated silica is an amorphous form of silica (silicon dioxide, SiO 2); it is a white, powdery material. Precipitated silica is produced by precipitation from a solution containing silicate salts. The three main classes of amorphous silica are pyrogenic silica, precipitated silica and silica gel.
Silica accelerates tooth wear, and high levels of silica in plants frequently eaten by herbivores may have developed as a defense mechanism against predation. [ 24 ] [ 25 ] Silica is also the primary component of rice husk ash , which is used, for example, in filtration and as supplementary cementitious material (SCM) in cement and concrete ...
Diatomite rock sample from Sisquoc Formation Scanning electron micrograph of diatomaceous earth. Diatomaceous earth (/ ˌ d aɪ. ə t ə ˈ m eɪ ʃ ə s / DY-ə-tə-MAY-shəs), also known as diatomite (/ d aɪ ˈ æ t ə m aɪ t / dy-AT-ə-myte), celite, or kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder.
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer -scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum. In the last case, the material is properly called silica ...
Wollastonite is a calcium inosilicate mineral (Ca Si O 3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature and pressure, which sometimes occurs in the presence of silica-bearing fluids as in skarns [7] or in contact with metamorphic rocks.