Kirchhoffite is an extremely rare cesium-borosilicate mineral belonging to the gismondine group of zeolites. It typically occurs as small, clear, platy crystals found in specialized hydrothermal environments within granite. Due to its rarity and restricted geological occurrence, it is primarily sought after by advanced mineral collectors.
Is this kirchhoffite?
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 kirchhoffite with a known reference. Kirchhoffite sits at Mohs 4.5-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kirchhoffite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kirchhoffite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals.
Often confused with
Kirchhoffite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside kirchhoffite
Minerals reported to co-occur with kirchhoffite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CsBSi₂O₆
- Mohs hardness
- 4.5-5
- Density
- 2.42 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Granitic Rocks
- Typical price
- expensive
Where rockhounds find kirchhoffite
Classic worldwide localities
- Kirchhoffite locality, Russia
- Piz Giuv, Switzerland
Field-hunting tip
Look in hydrothermal veins in granitic rocks country — that is the host setting where kirchhoffite typically forms. If you start seeing quartz, adularia, chlorite 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 kirchhoffite on the map
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