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, 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?+
Where is magnesiostaurolite found?+
How much is magnesiostaurolite worth?+
What rocks look like magnesiostaurolite?+
What minerals are found with magnesiostaurolite?+
What kind of rock does magnesiostaurolite form in?+
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Find magnesiostaurolite on the map
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