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 — that is 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.
