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Piemontite is a sorosilicate mineral in the monoclinic crystal system with the chemical formula . It is a member of the epidote group.Mindat reference page for Piemontite
/ref> Red to reddish-brown or red-black in color, piemontite has a red streak (mineralogy), streak and a vitreous lustre (mineralogy), lustre. Manganese (Mn3+) causes the red color. The type locality (geology), type locality is the Prabornaz Mine, in Saint-Marcel, Italy, Saint-Marcel, Aosta Valley, Italy. It occurs metamorphic rocks of the greenschist to amphibolite metamorphic facies and in low-temperature hydrothermal veins in altered volcanic rocks. It also occurs in Metasomatism, metasomatized deposits of manganese ore. Associated minerals include: epidote, tremolite, glaucophane, orthoclase, quartz and calcite.
/ref> Red to reddish-brown or red-black in color, piemontite has a red streak (mineralogy), streak and a vitreous lustre (mineralogy), lustre. Manganese (Mn3+) causes the red color. The type locality (geology), type locality is the Prabornaz Mine, in Saint-Marcel, Italy, Saint-Marcel, Aosta Valley, Italy. It occurs metamorphic rocks of the greenschist to amphibolite metamorphic facies and in low-temperature hydrothermal veins in altered volcanic rocks. It also occurs in Metasomatism, metasomatized deposits of manganese ore. Associated minerals include: epidote, tremolite, glaucophane, orthoclase, quartz and calcite.
References
Epidote group Calcium minerals Aluminium minerals Manganese(III) minerals Monoclinic minerals Minerals in space group 11 {{silicate-mineral-stub