Search results
Results from the WOW.Com Content Network
Peridot (/ ˈ p ɛ r ɪ ˌ d ɒ t,-ˌ d oʊ / PERR-ih-dot, -doh), sometimes called chrysolite, is a yellow-green transparent variety of olivine.Peridot is one of the few gemstones that occur in only one color.
It is often found in minute micaceous aggregates (with individual plates barely visible), as a major component of chromium rich phyllitic or schistose metamorphic rocks of the greenschist facies. Verdite is a type of metamorphic rock made mostly of an impure, often multicolored, variety of fuchsite. It is used for ornamental carvings.
Peridotite is named for the gemstone peridot, a glassy green gem originally mined on St. John's Island in the Red Sea [65] and now mined on the San Carlos Apache Indian Reservation in Arizona. [ 66 ] Peridotite that has been hydrated at low temperatures is the protolith for serpentinite , which may include chrysotile asbestos (a form of ...
While gem beryls are ordinarily found in pegmatites and certain metamorphic stones, red beryl occurs in topaz-bearing rhyolites. [53] It is formed by crystallizing under low pressure and high temperature from a pneumatolytic phase along fractures or within near-surface miarolitic cavities of the rhyolite.
Chlorite schist, a type of greenschist Greenschist (prasinite) at Cap Corse in Corsica, France Greenschist (epidote) from Itogon, Benguet, Philippines. Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically 300–450 °C (570–840 °F) and 2–10 kilobars (29,000–145,000 psi). [1]
Ammolite (organic; also a gemstone) Amosite (asbestiform grunerite) Antozonite (variety of fluorite) Anyolite (metamorphic rock - zoisite, ruby, and hornblende) Aquamarine (light blue variety of beryl) Argentite (high temperature form of acanthite) Asbestos (fibrous serpentine- or amphibole minerals) Auerlite (variety of thorite)
Metamorphic grade is an informal indication of the amount or degree of metamorphism. [78] In the Barrovian sequence (described by George Barrow in zones of ...
Epidote is an abundant rock-forming mineral, but one of secondary origin. It occurs in marble and schistose rocks of metamorphic origin. It is also a product of hydrothermal alteration of various minerals (feldspars, micas, pyroxenes, amphiboles, garnets, and others) composing igneous rocks.