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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.
Pargasite or pargasitic hornblende is a complex inosilicate mineral of the amphibole group with formula NaCa 2 (Mg 4 Al)(Si 6 Al 2)O 22 (OH) 2. It was first described for an occurrence in Pargas, Finland in 1814 and named for the locality. [6] It occurs in high temperature regional metamorphic rocks and in the skarns within contact aureoles ...
Edenite or edenitic hornblende is a double chain silicate mineral of the amphibole group with the general chemical composition NaCa 2 Mg 5 (Si 7 Al)O 22 (OH) 2. Edenite is named for the locality of Edenville, Orange County, New York, where it was first described. [4]
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.
Plagioclase phenocrysts (white) and hornblende phenocryst (dark; intergrown with plagioclase) are set in a fine matrix of plagioclase laths that show flow structure. Rocks can be classified according to the nature, size and abundance of phenocrysts, and the presence or absence of phenocrysts is often noted when a rock name is determined.
Dacite consists mostly of plagioclase feldspar and quartz with biotite, hornblende, and pyroxene (augite or enstatite). The quartz appears as rounded, corroded phenocrysts, or as an element of the ground-mass. [3] The plagioclase in dacite ranges from oligoclase to andesine and labradorite.
Ferro-ferri-hornblende is an amphibole-supergroup mineral with the formula ☐Ca 2 (Fe 2+ 4 Fe 3+)(Si 7 Al)O 22 (OH) 2. It contains essential vacancy (☐). It contains essential vacancy (☐). It was discovered in the Traversella mine, Canavese, Torino, Piedmont , Italy.
Diorite is an intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and sometimes pyroxene. The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite.