amphibole optical properties
Identification: Hornblende – (Na, K)0-1Ca2(Mg, Fe 2+, Fe3+, Al) 5(Si, Al)8O22(OH)2 – Hand Sample: Black in color with a vitreous luster. It has been known to be used in nearly a pure form as a blown on sound proofing in buildings like movie theaters. The chains are arranged such that the characteristic amphibole cleavage is 56° –124° (see your lecture notes). The contact aureoles produced in siliceous limestones and dolomites, called skarns or calc-silicate rocks, characteristically contain metamorphic amphiboles such as tremolite or actinolite. Because of their relative instability to chemical weathering at the Earth’s surface, amphiboles make up only a minor constituent in most sedimentary rocks. Amphiboles crystallize into two crystal systems, monoclinic and orthorhombic. It also occurs as phenocrysts in andesite lavas that contained enough water for amphiboles to form. Within the tables, minerals are arranged by colour so as to help with identification. The specific gravity values of amphiboles range from about 2.9 to 3.6. In addition, Wylie (21) noted that mono-clinic amphiboles (e.g., tremolite and actinolite) yield parallel extinction when they occur as fibers, instead of the … Sodium Amphibole Subgroup mineral data, information about Sodium Amphibole Subgroup, its properties and worldwide locations. Richterite occurs as a hydrothermal product and in veins in alkaline igneous rocks. Hardness and Strength of Amphibolite Hornblende is characteristic of some medium-grade metamorphic rocks known as amphibolites, in which hornblende and plagioclase are the major constituents. Richterite-winchite occurs in hydrothermally metamorphosed limestones. Magnesium-rich anthophyllites are found along contact zones of granitic dikes intruding ultramafic rocks (those rich in iron and magnesium). A .gov website belongs to an official government organization in the United States. Share sensitive information only on official, secure websites. Amphibole asbestos has straight, needle-like fibers that are more brittle than those of serpentine asbestos and are more limited in their ability to be fabricated. Secure .gov websites use HTTPS Glaucophane and riebeckite are usually blue. https://www.nist.gov/publications/optical-properties-amphibole-asbestos, Webmaster | Contact Us | Our Other Offices, actinolite, microscopy, optical properties, refractive index, tremolite, Created August 26, 2016, Updated February 17, 2017, Manufacturing Extension Partnership (MEP). Gedrite and cummingtonite coexist with garnet in rocks enriched in aluminum and iron. Glaucophane associated with jadeite, lawsonite, and calcite or aragonite is the characteristic assemblage found in high-pressure, low-temperature metamorphic rocks called blueschists, which have a blue colour imparted by the glaucophane. Hastingsite is found in granites and alkali-rich intrusives such as syenites. Amphiboles yield water when heated in a closed tube and … The optical properties of 16 fibrous tremolite, actinolite, and ferro-actinolite samples from Verkouteren and Wylie (2000) are described. Glaucophane occurs only in such metamorphic rocks as schist, eclogite, and marble. Amphiboles occur in contact metamorphic aureoles around igneous intrusions. The latter also may occur in regional metamorphic schists. Dehydration of amphiboles in the lower crust or mantle may be an important source of water that aids in the generation of magmas from partial melting processes. The presence of tremolite implies a relatively low grade of metamorphism as tremolite breaks down to form the pyroxene diopside in the presence of calcite and quartz at elevated temperatures. Amphiboles may be inexperienced, black, colorless, white, yellow, blue, or brown. These tables provide a concise summary of the properties of a range of common minerals. Common hornblende is typically black. The most common amphibole is hornblende and if it was fibrous it would be considered ‘amosite.’ It is commonly used in boiler and pipe insulation. Iron-free varieties of tremolite containing manganese can have a lavender colour. They are an isomorphous mixture of three molecules; a calcium-iron-magnesium silicate, an aluminium-iron-magnesium silicate, and an iron-magnesium silicate.The name hornblende is applied to a group of minerals that can be distinguished from each … Blueschists have basaltic bulk compositions and may also contain riebeckite. Hornblende is a inosilicate amphibole minerals, which are two type hornblende minerals. Amphibole - Amphibole - Physical properties: Long prismatic, acicular, or fibrous crystal habit, Mohs hardness between 5 and 6, and two directions of cleavage intersecting at approximately 56° and 124° generally suffice to identify amphiboles in hand specimens. as muscovite and for amphibole, but the ages of both of these minerals can be completely reset at temperatures that have little or no effect on zircon.…, …pyroxenes differ compositionally from the amphiboles in two major respects. Many different amphiboles may be contained in regional metamorphic rocks. Die Amphibolgruppe umfasst Silikate, die sich strukturell durch Doppelketten aus eckenverknüpften SiO4-Tetraedern auszeichnen und deren Zusammensetzung der folgenden verallgemeinerten Summenformel genügt: A0-1B2C5T8O22(OH)2.