Ammonioleucite is a rare tectosilicate mineral characterized by its ammonium content replacing potassium in the leucite structure. It typically occurs as small, sharp trapezohedral crystals within cavities of alkaline volcanic rocks and is often discovered through microscopic analysis of mineral suites.
Is this ammonioleucite?
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 ammonioleucite with a known reference. Ammonioleucite 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: resinous to vitreous.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: trapezohedral crystals.
Often confused with
Ammonioleucite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ammonioleucite
Minerals reported to co-occur with ammonioleucite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)AlSi₂O₆
- Mohs hardness
- 5.5-6
- Density
- 2.29 g/cm³
- Colors
- Streak
- White
- Luster
- Resinous to vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Trapezohedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In veinlets, fractures, and cavities in hydrothermally altered crystalline schist, as powdery pseudomorphous replacements of analcime crystals
Where rockhounds find ammonioleucite
Classic worldwide localities
- Tatarazawa quarry, Fujioka, Gumma Prefecture, Japan
Field-hunting tip
Where it forms: In veinlets, fractures, and cavities in hydrothermally altered crystalline schist, as powdery pseudomorphous replacements of analcime crystals. If you start seeing analcime, dolomite in float, you are in the right ground. Typical habit: trapezohedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ammonioleucite?+
Where is ammonioleucite found?+
What rocks look like ammonioleucite?+
What minerals are found with ammonioleucite?+
What kind of rock does ammonioleucite form in?+
What is ammonioleucite used for?+
Find ammonioleucite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
