Staurolite crosses are famous natural penetration twins where two crystals intersect at specific angles to form a cross shape. They are typically found weathered out of mica-rich metamorphic schists, leaving behind durable, brownish, cross-shaped specimens that are highly prized by collectors as talismans.
Is this staurolite cross?
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 staurolite cross with a known reference. Staurolite Cross 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. Staurolite Cross leaves a white to grayish streak.
- 3Read the lusterHold the specimen under a strong light. Staurolite Cross typically shows a subvitreous to resinous luster.
- 4Match the color rangeCompare against the expected color range: brown, reddish-brown, yellowish-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: penetration twins.
Often confused with
Staurolite Cross vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Staurolite Cross leaves white to grayish, Chiastolite leaves white; luster reads subvitreous to resinous on Staurolite Cross and vitreous on Chiastolite.
How to tell apart: Streak differs, so Staurolite Cross leaves white to grayish, Andalusite leaves white; luster reads subvitreous to resinous on Staurolite Cross and vitreous on Andalusite.
Often found alongside staurolite cross
Minerals reported to co-occur with staurolite cross. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺₂Al₉Si₄O₂₃(OH)
- Mohs hardness
- 7-7.5
- Density
- 3.7-3.8 g/cm³
- Streak
- White to Grayish
- Luster
- Subvitreous to Resinous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Penetration Twins
- Cleavage
- Distinct On {010}
- Rarity
- Common
- Uses
- Collector, Jewelry
- Host rock
- Metamorphic Schists and Gneisses
- Typical price
- $5-50 depending on twinning perfection and size
Where rockhounds find staurolite cross
Classic worldwide localities
- Patrick County, Virginia, USA
- Fannin County, Georgia, USA
- Brittany, France
- Russia
Field-hunting tip
Look in metamorphic schists and gneisses country, the host setting where staurolite cross typically forms. If you start seeing kyanite, garnet, muscovite in float, you are in the right ground. Field specimens usually show a penetration twins habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find staurolite cross on the map
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