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 — 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 — 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 — that is 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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