Piemontite is a manganese-rich member of the epidote group, easily distinguished by its distinctive reddish-brown to cherry-red color. It typically forms in low-grade metamorphic rocks and is highly prized by collectors for its rare, well-terminated prismatic crystals or vibrant massive chunks found in alpine-type veins.
Is this piemontite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch piemontite with a known reference. Piemontite sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Piemontite leaves a reddish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Piemontite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, reddish-brown, pink, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Piemontite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Piemontite leaves reddish-brown, Epidote leaves white.
How to tell apart: Streak differs — Piemontite leaves reddish-brown, Allanite leaves gray; luster reads vitreous on Piemontite and submetallic on Allanite.
How to tell apart: Streak differs — Piemontite leaves reddish-brown, Clinozoisite leaves white.
Often found alongside piemontite
Minerals reported to co-occur with piemontite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mn³⁺Al₂(Si₂O₇)(SiO₄)O(OH)
- Mohs hardness
- 6-6.5
- Density
- 3.4-3.6 g/cm³
- Streak
- Reddish-brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Massive, Granular
- Cleavage
- Perfect
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Metamorphic Rocks, Specifically Manganese-rich Schists and Marbles
- Typical price
- $10-50 per specimen depending on crystal size and quality
Where rockhounds find piemontite
Classic worldwide localities
- Saint-Marcel, Italy
- Jakobsberg, Sweden
- Oman
- Japan
- California, USA
Field-hunting tip
Look in metamorphic rocks, specifically manganese-rich schists and marbles country — that is the host setting where piemontite typically forms. If you start seeing quartz, calcite, braunite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify piemontite?+
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How much is piemontite worth?+
What rocks look like piemontite?+
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Find piemontite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
