What is the composition of amphibolite?
The mineral composition of the amphibolites is simple and mostly contains hornblende and plagioclase, with variable amounts of anthophyllite, garnet, mica, quartz, and epidote. The rocks may originate from pelitic sediments, with amphibole (hornblende), plagioclase, and typically include green pyroxene.
What is hornblende chemical formula?
hornblende, calcium-rich amphibole mineral that is monoclinic in crystal structure. Hornblende’s generalized chemical formula is (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22 (OH)2.
What is the chemical formula for olivine?
Olivine is a magnesium iron silicate with the formula (Mg2+, Fe2+)2SiO4. End members are forsterite (Mg2SiO4) and fayalite (Fe2+2SiO4). Olivine is an abundant mineral in most mafic igneous rocks and the most abundant mineral in the earth’s upper mantle.
What is massive amphibolite?
Amphibolite is a grouping of rocks composed mainly of amphibole and plagioclase, with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure. The small flakes of black and white in the rock often give it a salt-and-pepper appearance.
How is the amphibolite formed?
How Does Amphibolite Form? Amphibolite is a rock of convergent plate boundaries where heat and pressure cause regional metamorphism. It can be produced through the metamorphism of mafic igneous rocks such as basalt and gabbro, or from the metamorphism of clay-rich sedimentary rocks such as marl or graywacke.
Is augite a Pleochroic?
Color: Colorless, pale green, pale brown, green, greenish-yellow, pale yellow green, grayish green, violet. Zonal structure is sometimes present. Pleochroism: Absent or weak; it is best shown in {100} sections.
What is the chemical formula of olivine?
What is the chemical formula for amphibole?
The chemical composition and variability of the amphiboles may be expressed by the general formula AB 2 C 5 T 8 O 22 W 2, where: A = □, Na, K, Ca, Pb 2+ B = Li, Na, Mg, Fe 2+, Mn 2+, Ca
What is the Cr2O3 content of amphiboles?
Low Cr 2 O 3 amphiboles are mostly associated with garnet, whereas high Cr 2 O 3 amphiboles are mostly associated with Cpx. TiO 2 contents are mostly between 0.25 and 0.45 wt% but are less than 0.2 wt% in sample VI01/04.
What is the chemical formula for riebeckite?
Riebeckite is a sodium -rich member of the amphibole group of silicate minerals, chemical formula Na 2 (Fe 2+3 Fe 3+2 )Si 8 O 22 (OH) 2. It forms a solid solution series with magnesioriebeckite.
What is amphibole supergroup?
The amphibole supergroup is a group of more then hundred rock-forming silicates. This article provides general introduction to structure, physical properties and chemical composition of amphiboles.
