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, 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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