Kalsilite is a rare potassium-dominant member of the nepheline group, typically occurring in silica-undersaturated volcanic rocks. It is visually difficult to distinguish from nepheline without X-ray diffraction or chemical analysis. Collectors typically seek it in association with rare volcanic suites in the Eifel region or its type locality in Uganda.
Is this kalsilite?
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 kalsilite with a known reference. Kalsilite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kalsilite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kalsilite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, pale yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: equant to prismatic crystals, often as microscopic grains or interstitial fillings.
Often confused with
Kalsilite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside kalsilite
Minerals reported to co-occur with kalsilite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KAlSiO₄
- Mohs hardness
- 6
- Density
- 2.59 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Equant to Prismatic Crystals, Often as Microscopic Grains or Interstitial Fillings
- Cleavage
- Distinct Basal
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Potassic Alkaline Volcanic Rocks
- Typical price
- varies significantly by specimen availability
Where rockhounds find kalsilite
Classic worldwide localities
- Kaiso region, Uganda
- Eifel Mountains, Germany
- Vesuvius area, Italy
- Kola Peninsula, Russia
Field-hunting tip
Look in potassic alkaline volcanic rocks country, the host setting where kalsilite typically forms. If you start seeing leucite, nepheline, melilite in float, you are in the right ground. Field specimens usually show a equant to prismatic crystals, often as microscopic grains or interstitial fillings habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kalsilite?+
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How much is kalsilite worth?+
What rocks look like kalsilite?+
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Find kalsilite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
