Piemontite
(same H-M symbol)
Piemontite is a sorosilicate mineral in the monoclinic crystal system with the chemical formula Ca2(Al,Mn3+,Fe3+)3(SiO4)(Si2O7)O(OH).[2] It is a member of the epidote group.[4]
Red to reddish-brown or red-black in color, piemontite has a red streak and a vitreous lustre.[4] Manganese (Mn3+) causes the red color.[5]
The type locality is the Prabornaz Mine, in Saint-Marcel, Aosta Valley, Italy.[4]
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 metasomatized deposits of manganese ore. Associated minerals include: epidote, tremolite, glaucophane, orthoclase, quartz and calcite.[2]
![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/87/Piemontite-Quartz-Calcite-188379.jpg/220px-Piemontite-Quartz-Calcite-188379.jpg)
References
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b c Handbook of Mineralogy
- ^ Webmineral.com website
- ^ a b c d Mindat reference page for Piemontite
- ^ "Minerals Colored by Metal Ions". minerals.gps.caltech.edu. Retrieved 2023-03-01.
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Mixed |
- Axinite (borosilicate)
- Geigerite (arsenate)
- Manganese nodule (various)
- Samsonite (sulfosalt)
- Zincobotryogen (sulfate)
- Wolframite (tungstate)
- Hübnerite (tungstate)
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