Leucite is a rock-forming mineral recognized by its distinctive trapezohedral crystal habit, which often appears as isometric crystals that are actually pseudocubic. It is primarily found in potassium-rich volcanic rocks and is often discovered in altered, cloudy, or white-colored masses within lava flows.
Is this leucite?
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 leucite with a known reference. Leucite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, gray, colorless, yellow gray.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: crystalline.
Often confused with
Leucite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside leucite
Minerals reported to co-occur with leucite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KAlSi₂O₆
- Mohs hardness
- 5.5-6
- Density
- 2.45-2.50 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Tetragonal
- Crystal habit
- Crystalline
- Cleavage
- Very poor on {110}
- Rarity
- Common
- Uses
- Collector, Scientific research
- Host rock
- With potassium-rich mafic and ultramafic lavas and hypabyssal rocks, and may almost entirely compose them
Where rockhounds find leucite
Classic worldwide localities
- Leucite Hills, Sweetwater Co., Wyoming, USA
- Bear Paw Mountains, Hill Co., Montana, USA
- Magnet Cove, Hot Spring Co., Arkansas, USA
- Italy, as at Vesuvius, Monte Somma, and Roccamonfina, Campania
- Villa Senni, Frascati, and Ariccia, Lazio
- Vulcano, Lipari Islands
Field-hunting tip
Where it forms: With potassium-rich mafic and ultramafic lavas and hypabyssal rocks, and may almost entirely compose them. If you start seeing potassic feldspar, nepheline, analcime in float, you are in the right ground. Typical habit: crystalline. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify leucite?+
Where is leucite found?+
What rocks look like leucite?+
What minerals are found with leucite?+
What kind of rock does leucite form in?+
What is leucite used for?+
Find leucite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
