Piedmontite is a distinct, manganese-bearing member of the epidote group, easily recognized by its vibrant reddish-pink to violet color. It is typically found as prismatic crystals or fibrous masses within regional metamorphic rocks and manganese-rich hydrothermal deposits.
Is this piedmontite?
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 piedmontite with a known reference. Piedmontite sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Piedmontite leaves a reddish-pink streak.
- 3Read the lusterHold the specimen under a strong light. Piedmontite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, reddish-brown, pink, violet.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates, fibrous, massive.
Often confused with
Piedmontite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Piedmontite leaves reddish-pink, Epidote leaves white.
How to tell apart: Streak differs — Piedmontite leaves reddish-pink, Clinozoisite leaves white.
How to tell apart: Streak differs — Piedmontite leaves reddish-pink, Allanite leaves gray; luster reads vitreous on Piedmontite and submetallic on Allanite.
Often found alongside piedmontite
Minerals reported to co-occur with piedmontite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Al₂(Mn³⁺,Fe³⁺)(SiO₄)(Si₂O₇)O(OH)
- Mohs hardness
- 6-7
- Density
- 3.4-3.5 g/cm³
- Streak
- Reddish-pink
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Radial Aggregates, Fibrous, Massive
- Cleavage
- Perfect Basal
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Metamorphic Rocks, Specifically Manganese-rich Schists and Hydrothermal Veins
- Typical price
- $10-100 per specimen
Where rockhounds find piedmontite
1 mapped spotsClassic worldwide localities
- San Quirico, Italy
- Piedmont, Italy
- Hakone, Japan
- Ojo Caliente, USA
- Gloucestershire, United Kingdom
Field-hunting tip
Look in metamorphic rocks, specifically manganese-rich schists and hydrothermal veins country — that is the host setting where piedmontite typically forms. If you start seeing quartz, calcite, tremolite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial aggregates, fibrous, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Pennsylvania — start trip planning there.
Common questions
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Find piedmontite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
