Zussmanite is a rare phyllosilicate mineral typically found in high-pressure, low-temperature metamorphic environments such as blueschist facies. It usually appears as fine-grained, platy, or radiating aggregates with a distinct green or brown coloration. It is primarily known from its type locality near Laytonville, California, where it forms in association with other silicates.
Is this zussmanite?
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 zussmanite with a known reference. Zussmanite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Zussmanite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Zussmanite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals.
Often confused with
Zussmanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Zussmanite leaves white, Stilpnomelane leaves yellowish-brown to greenish-black; luster reads vitreous on Zussmanite and pearly on Stilpnomelane.
How to tell apart: Luster reads vitreous on Zussmanite and pearly on Biotite.
Often found alongside zussmanite
Minerals reported to co-occur with zussmanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K(Fe,Mg,Mn)₁₃(Si,Al)₁₈O₄₂(OH)₁₄
- Mohs hardness
- 3
- Density
- 3.16 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Blueschist Facies
- Typical price
- $20-150 per specimen
Where rockhounds find zussmanite
Classic worldwide localities
- Laytonville, California, USA
Field-hunting tip
Look in metamorphic blueschist facies country, the host setting where zussmanite typically forms. If you start seeing quartz, stilpnomelane, riebeckite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find zussmanite on the map
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