Balangeroite is a rare, asbestiform magnesium silicate primarily identified in the serpentinite bodies of the Italian Alps. It typically presents as light brown to reddish-brown fibrous masses and is almost exclusively found in the Balangero mine area.
Is this balangeroite?
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 balangeroite with a known reference. Balangeroite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, greasy.
- 4Match the color rangeCompare against the expected color range: brownish yellow, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous.
Often confused with
Balangeroite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Balangeroite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Balangeroite leaves brownish white, Chrysotile leaves white; luster reads vitreous, greasy on Balangeroite and silky on Chrysotile.
How to tell apart: Tremolite is the harder of the two (Mohs 5-6 vs. 3.5); streak differs, so Balangeroite leaves brownish white, Tremolite leaves white.
How to tell apart: Streak differs, so Balangeroite leaves brownish white, Antigorite leaves white; luster reads vitreous, greasy on Balangeroite and resinous, greasy, silky, waxy, earthy on Antigorite.
Often found alongside balangeroite
Minerals reported to co-occur with balangeroite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₄₂Si₁₆O₅₄(OH)₄₀
- Mohs hardness
- 3.5
- Density
- 2.96-3.10 g/cm³
- Streak
- Brownish white
- Luster
- Vitreous, greasy
- Transparency
- Transparent only in thin section
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous
- Cleavage
- One or more on fhk0g are very good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In schistose serpentinite in proximity to a large ultramafic massif
Where rockhounds find balangeroite
Classic worldwide localities
- Balangero (San Vittore) mine and at Ponte del Diavolo, Lanzo Valley, and from Santa Maria della Neve, Fiano, Piedmont, Italy
Field-hunting tip
Where it forms: In schistose serpentinite in proximity to a large ultramafic massif. If you start seeing chrysotile, magnetite, olivine in float, you are in the right ground. Typical habit: fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify balangeroite?+
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Is balangeroite safe to handle?+
What rocks look like balangeroite?+
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Find balangeroite on the map
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