Turtmannite is a rare manganese vanadate that forms bright yellow flakes. It occurs in metamorphosed (upper greenschist facies) jacobsite-rich Fe-Mn ores in paleokarst. Associated minerals include jacobsite, kutnohorite and baryte. It was first described from Turtmann Valley, Valais, Switzerland.
Is this turtmannite?
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 turtmannite with a known reference. Turtmannite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Turtmannite leaves a colorless streak.
- 3Read the lusterHold the specimen under a strong light. Turtmannite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: bright yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: flakes.
Often confused with
Turtmannite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Turtmannite leaves colorless, Tilasite leaves white.
How to tell apart: Streak differs, so Turtmannite leaves colorless, Magnussonite leaves white; luster reads vitreous on Turtmannite and vitreous to adamantine on Magnussonite.
Often found alongside turtmannite
Minerals reported to co-occur with turtmannite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₂₅O₅(VO₄)₃(SiO₄)₃(OH)₂₀
- Mohs hardness
- 4-5
- Density
- 3.6-4.0 g/cm³
- Colors
- Streak
- Colorless
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Flakes
- Cleavage
- Perfect On {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Metamorphic Rocks
Where rockhounds find turtmannite
Classic worldwide localities
- Turtmanntal, Switzerland
- Långban, Sweden
Field-hunting tip
Look in hydrothermal veins in metamorphic rocks country, the host setting where turtmannite typically forms. If you start seeing barite, hematite, quartz in float, you are in the right ground. Field specimens usually show a flakes habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify turtmannite?+
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Find turtmannite on the map
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