Lavoisierite is a rare manganese silicate mineral typically found as small, prismatic crystals in high-grade metamorphic deposits. It is structurally related to gaudefroyite and is highly prized by collectors for its limited locality and unique chemical composition.
Is this lavoisierite?
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 lavoisierite with a known reference. Lavoisierite 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. Lavoisierite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Lavoisierite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark brown, reddish-brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals.
Often confused with
Lavoisierite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Lavoisierite and submetallic on Gaudefroyite.
How to tell apart: Streak differs — Lavoisierite leaves brown, Braunite leaves black; luster reads vitreous on Lavoisierite and submetallic on Braunite.
Often found alongside lavoisierite
Minerals reported to co-occur with lavoisierite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn³⁺₈Al₂(Si₂O₇)O₃(OH)₃
- Mohs hardness
- 6-7
- Density
- 3.58 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Manganese-rich Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find lavoisierite
Classic worldwide localities
- Saint-Marcel, Aosta Valley, Italy
Field-hunting tip
Look in metamorphic manganese-rich rocks country — that is the host setting where lavoisierite typically forms. If you start seeing quartz, braunite, hollandite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find lavoisierite on the map
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