Piemontite
Mineral Ca2(Al2Mn)(SiO4)(Si2O7)O(OH)
Also called Piedmontite
About it
Manganese epidote in reddish-purple prisms and grains that colour some schists and porphyries; named for Piemonte, Italy, and also found in Japan.
- Type
- Mineral
- Group
- Silicate (sorosilicate), epidote group
- Formula
- Ca2(Al2Mn)(SiO4)(Si2O7)O(OH)
- Hardness (Mohs)
- 6–6.5
- Specific gravity
- 3.45–3.52
- Streak
- red
- Lustre
- vitreous (glassy)
- Crystal system
- Monoclinic
- Colours
- red, reddish brown, reddish violet, purple
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- perfect in one direction
Typical values: real specimens vary. For more, see mindat.org.