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Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. [1][2][3] In mineralogy, silica (silicon dioxide, SiO2) is usually considered a silicate mineral rather than an oxide mineral.
- Overview
- Structure
silicate mineral, any of a large group of silicon-oxygen compounds that are widely distributed throughout much of the solar system. A brief treatment of silicate minerals follows. For full treatment, see mineral: Silicates.
The silicates make up about 95 percent of Earth’s crust and upper mantle, occurring as the major constituents of most igneous rocks and in appreciable quantities in sedimentary and metamorphic varieties as well. They also are important constituents of lunar samples, meteorites, and most asteroids. In addition, planetary probes have detected their occurrence on the surfaces of Mercury, Venus, and Mars. Of the approximately 600 known silicate minerals, only a few dozen—a group that includes the feldspars, amphiboles, pyroxenes, micas, olivines, feldspathoids, and zeolites—are significant in rock formation.
The basic structural unit of all silicate minerals is the silicon tetrahedron in which one silicon atom is surrounded by and bonded to (i.e., coordinated with) four oxygen atoms, each at the corner of a regular tetrahedron. These SiO4 tetrahedral units can share oxygen atoms and be linked in a variety of ways, which results in different structures. The topology of these structures forms the basis for silicate classification. For example, nesosilicates are minerals whose structure are made up of independent silicate tetrahedrons. Sorosilicates are silicate minerals consisting of double tetrahedral groups in which one oxygen atom is shared by two tetrahedrons. Cyclosilicates, in contrast, are arranged in rings made up of three, four, or six tetrahedral units. Inosilicates show a single-chain structure wherein each tetrahedron shares two oxygen atoms. Phyllosilicates have a sheet structure in which each tetrahedron shares one oxygen atom with each of three other tetrahedrons. Tectosilicates show a three-dimensional network of tetrahedrons, with each tetrahedral unit sharing all of its oxygen atoms.
Details of the linkage of tetrahedrons became known early in the 20th century when X-ray diffraction made the determination of crystal structure possible. Prior to this, the classification of silicates was based on chemical and physical similarities, which often proved to be ambiguous. Although many properties of a silicate mineral group are determined by tetrahedral linkage, an equally important factor is the type and location of other atoms in the structure.
- The Editors of Encyclopaedia Britannica
Silica mineral, any of the forms of silicon dioxide (SiO2), including quartz, tridymite, cristobalite, coesite, stishovite, lechatelierite, and chalcedony. Various kinds of silica minerals have been produced synthetically; one is keatite.
Apr 24, 2024 · The vast majority of the minerals that make up the rocks of Earth’s crust are silicate minerals. These include minerals such as quartz, feldspar, mica, amphibole, pyroxene, olivine, and a variety of clay minerals.
A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula [SiO (4-2x)− 4−x] n, where 0 ≤ x < 2. The family includes orthosilicate SiO 4− 4 (x = 0), metasilicate SiO 2− 3 (x = 1), and pyrosilicate Si 2 O 6− 7 (x = 0.5, n = 2).
Aug 25, 2024 · Mineral - Silicates, Crystalline, Structure: The silicates, owing to their abundance on Earth, constitute the most important mineral class. Approximately 25 percent of all known minerals and 40 percent of the most common ones are silicates; the igneous rocks that make up more than 90 percent of Earth’s crust are composed of virtually all ...
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The vast majority of the minerals that make up the rocks of Earth’s crust are silicate minerals. These include minerals such as quartz, feldspar, mica, amphibole, pyroxene, olivine, and a great variety of clay minerals.
