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Amphibole (/ ˈ æ m f ə b oʊ l / AM-fə-bohl) is a group of inosilicate minerals, forming prism or needlelike crystals, [1] composed of double chain SiO 4 tetrahedra , linked at the vertices and generally containing ions of iron and/or magnesium in their structures.
Amphibolite from Cape Cod, Massachusetts Garnet bearing amphibolite from Val di Fleres, Italy. Amphibolite (/ æ m ˈ f ɪ b ə l aɪ t /) is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz.
Hornblende is a complex inosilicate series of minerals. [6] It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks. The general formula is (Ca,Na) 2−3 (Mg,Fe,Al) 5 (Al,Si) 8 O 22 (OH,F) 2.
Actinolite is an amphibole silicate mineral with the chemical formula Ca 2 (Mg 4.5–2.5 Fe 2+ 0.5–2.5)Si 8 O 22 (OH) 2. Etymology.
Anthophyllite is an orthorhombic amphibole mineral: ☐Mg 2 Mg 5 Si 8 O 22 (OH) 2 (☐ is for a vacancy, a point defect in the crystal structure), magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. Some forms of anthophyllite are lamellar or fibrous and are classed as asbestos.
Cummingtonite is used to describe minerals of this formula with between 30 and 70 per cent Fe 7 Si 8 O 22 (OH) 2. Thus, cummingtonite is the series intermediate. Manganese also substitutes for (Fe,Mg) within cummingtonite amphibole, replacing B site atoms.
In geology and mineralogy, a mineral group is a set of mineral species with essentially the same crystal structure and composed of chemically similar elements. [1] Silicon-oxygen double chain in the anions of amphibole minerals. For example, the amphibole group consists of 15 or more mineral species, most of them with the general unit formula A ...
Kaersutite is a dark brown to black double-chain calcic titanium-bearing amphibole mineral with formula: NaCa 2 (Mg 3 Ti 4+ Al)(Si 6 Al 2)O 22 (O) 2. [6]Ferro-kaersutite is the divalent iron-rich endmember of the kaersutite group, with the iron replacing magnesium in the structure.