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Chert (/ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, [1] the mineral form of silicon dioxide (SiO 2). [2] Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.
Chalcedony, Agate, Onyx, Jasper, Aventurine, Tiger's eye, Rock Crystal, Amethyst, Citrine, Rose quartz, Milk quartz (or snow quartz), Carnelian: Another way to do it (preferences?): Chalcedony: Any cryptocrystalline quartz, although generally only used for white or lightly coloured material. Otherwise more specific names are used. Agate
Chalcedony (/ k æ l ˈ s ɛ d ə n i / kal-SED-ə-nee or / ˈ k æ l s ə ˌ d oʊ n i / KAL-sə-doh-nee) [2] is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. [3] These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic.
Carnelian (variety of quartz) Cementite (synthetic cohenite) Ceylonite (variety of spinel) Chalcedony (cryptocrystalline variety of quartz and moganite) Chiastolite (variety of andalusite) Chlorastrolite (variety of pumpellyite-(Mg)) Chrysoprase (green nickel bearing chalcedony) Chrysotile (group name - asbestiform serpentine) Citrine (yellow ...
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. [10] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...
Cryptocrystalline is a rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically [1] in thin section by transmitted polarized light. Among the sedimentary rocks, chert and flint are cryptocrystalline. Carbonado, a form of diamond, is also cryptocrystalline.
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1] [2] categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires. Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.
Chalcedony: traditionally a fibrous cryptocrystalline quartz var., more recently, a mixture of quartz and moganite. Structural groups are crystallographic groups that may contain minerals from more than one class/ subclass. Supergroups contain minerals from more than one class/ subclass. Anilite transforms to digenite during grinding.