Letovicite is a rare ammonium sulfate mineral primarily found in coal fire zones or fumarolic environments. It typically forms as delicate tabular crystals or crusts, and because it is highly water-soluble, collectors must store it in low-humidity environments to prevent dissolution.
Is this letovicite?
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 letovicite with a known reference. Letovicite sits at Mohs 1-2, 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: colorless, white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: microscopic crystals, platy, pseudo hexagonal.
Often confused with
Letovicite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside letovicite
Minerals reported to co-occur with letovicite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₃H(SO₄)₂
- Mohs hardness
- 1-2
- Density
- 1.83 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Microscopic crystals, platy, pseudo hexagonal
- Cleavage
- {001}, distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral, formed from burning coal (Czech Republic); deposited from hot springs (The Geysers, California, USA)
Where rockhounds find letovicite
Classic worldwide localities
- Found at The Geysers, Sonoma Co., California, USA
- Písěcná, near Letovice, Czech Republic
- Libušin, near Kladno, Czech Republic
- Radvanice, Czech Republic
- Ormosbánya, Hungary
Field-hunting tip
Where it forms: A rare secondary mineral, formed from burning coal (Czech Republic); deposited from hot springs (The Geysers, California, USA). If you start seeing sulfur, mascagnite, boussingaultite in float, you are in the right ground. Typical habit: microscopic crystals, platy, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
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Find letovicite on the map
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