Piemontite
| Piemontite | ||
|---|---|---|
Mohs scale hardness 6 – 6.5 | | |
| Luster | Vitreous | |
| Streak | Red | |
| Diaphaneity | Translucent to nearly opaque | |
| Density | 3.46 – 3.54 | |
| Optical properties | Biaxial (+) 2V = 64–106 | |
| Refractive index | nα = 1.725 – 1.756 nβ = 1.730 – 1.789 nγ = 1.750 – 1.832 | |
| Birefringence | δ = 0.025 – 0.076 | |
| Pleochroism | Visible | |
| Dispersion | r>v very strong | |
| References | [2][3][4] | |
Piemontite is a
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
It occurs
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]
Limpopo Province
, South Africa. Red piemontite microcrystals cover three sides of a doubly terminated quartz crystal. Size: 7.1 × 3.0 × 2.6 cm.References
- 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.
Wikimedia Commons has media related to Piemontite.
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