Magnesiostaurolite is a rare magnesium-dominant member of the staurolite group, often occurring in high-pressure metamorphic environments. It is best identified by its distinctive cruciform twinning habit and characteristic brown-to-reddish coloration in schists.
Is this magnesiostaurolite?
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 magnesiostaurolite with a known reference. Magnesiostaurolite sits at Mohs 7-7.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Magnesiostaurolite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Magnesiostaurolite typically shows a subvitreous luster.
- 4Match the color rangeCompare against the expected color range: reddish-brown, brown, yellow-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals often forming cruciform penetration twins.
Often confused with
Magnesiostaurolite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside magnesiostaurolite
Minerals reported to co-occur with magnesiostaurolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Fe²⁺)₂Al₉Si₄O₂₃(OH)
- Mohs hardness
- 7-7.5
- Density
- 3.6-3.8 g/cm³
- Streak
- White
- Luster
- Subvitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals Often Forming Cruciform Penetration Twins
- Cleavage
- Distinct On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- High-grade Metamorphic Rocks Such as Kyanite-bearing Schists and Gneisses
- Typical price
- $20-150 for mineral specimens
Where rockhounds find magnesiostaurolite
Classic worldwide localities
- Monte Rossa, Italy
- Switzerland
- Austria
Field-hunting tip
Look in high-grade metamorphic rocks such as kyanite-bearing schists and gneisses country — that is the host setting where magnesiostaurolite typically forms. If you start seeing kyanite, garnet, biotite in float, you are in the right ground. Field specimens usually show a prismatic crystals often forming cruciform penetration twins habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify magnesiostaurolite?+
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How much is magnesiostaurolite worth?+
What rocks look like magnesiostaurolite?+
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Find magnesiostaurolite on the map
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