Barroisite is a complex calcium-sodium amphibole typically found in metamorphic rocks like blueschists or amphibolites. It is difficult to distinguish from other amphiboles without specialized chemical analysis, usually appearing as dark, elongated prismatic crystals or fibrous masses.
Is this barroisite?
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 barroisite with a known reference. Barroisite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Barroisite leaves a white to light gray streak.
- 3Read the lusterHold the specimen under a strong light. Barroisite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, black, brownish-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic, fibrous, or granular aggregates.
Often confused with
Barroisite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Barroisite leaves white to light gray, Hornblende leaves grayish-white.
How to tell apart: Streak differs — Barroisite leaves white to light gray, Glaucophane leaves white.
How to tell apart: Streak differs — Barroisite leaves white to light gray, Actinolite leaves white; luster reads vitreous on Barroisite and vitreous to silky on Actinolite.
Often found alongside barroisite
Minerals reported to co-occur with barroisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(NaCa)(Mg₃AlFe³⁺)(AlSi₇)O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.2-3.4 g/cm³
- Streak
- White to Light Gray
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic, Fibrous, Or Granular Aggregates
- Cleavage
- Perfect Prismatic
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Rocks
- Typical price
- $20-100 per specimen
Where rockhounds find barroisite
Classic worldwide localities
- Barrois, France
- Alps
- Norway
- Scotland
Field-hunting tip
Look in metamorphic rocks country — that is the host setting where barroisite typically forms. If you start seeing epidote, albite, chlorite in float, you are in the right ground. Field specimens usually show a prismatic, fibrous, or granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find barroisite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
