Günterblassite is a rare phyllosilicate mineral discovered in the volcanic regions of the Eifel mountains in Germany. It typically forms thin, platy, pseudo-hexagonal crystals within the cavities of phonolitic rocks, often requiring magnification for clear identification.
Is this günterblassite?
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 günterblassite with a known reference. Günterblassite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Günterblassite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Günterblassite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, pseudo-hexagonal aggregates.
Often found alongside günterblassite
Minerals reported to co-occur with günterblassite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Ca,Na)₂(Fe,Mn,Mg)₇(Si,Al)₁₆O₃₈(OH)₂·8H₂O
- Mohs hardness
- 2
- Density
- 2.26 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Pseudo-hexagonal Aggregates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Vesicles in Phonolite
- Typical price
- $50-300 per specimen
Where rockhounds find günterblassite
Classic worldwide localities
- Eifel region, Germany
Field-hunting tip
Look in volcanic vesicles in phonolite country — that is the host setting where günterblassite typically forms. If you start seeing tachyhydrite, goethite, hematite in float, you are in the right ground. Field specimens usually show a platy crystals, pseudo-hexagonal aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find günterblassite on the map
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