Russoite is a rare ammonium-bearing arsenic-antimony oxide mineral typically found in volcanic fumaroles. It forms distinct yellow, platy, or tabular crystals associated with other arsenic-rich minerals in high-temperature volcanic settings.
Is this russoite?
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 russoite with a known reference. Russoite sits at Mohs 1.5-2, 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: hexagonal. Typical habit: platy crystals, crusts.
Often confused with
Russoite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside russoite
Minerals reported to co-occur with russoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)ClAs₂O₃(H₂O)₀.₅
- Mohs hardness
- 1.5-2
- Density
- 2.89 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Platy crystals, crusts
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Found as a sublimate around a volcanic fumarole
Where rockhounds find russoite
Classic worldwide localities
- La Fossa crater, Vulcano, Aeolian Islands, Italy
Field-hunting tip
Where it forms: Found as a sublimate around a volcanic fumarole. If you start seeing alacránite, dimorphite, realgar in float, you are in the right ground. Typical habit: platy crystals, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify russoite?+
Where is russoite found?+
Is russoite safe to handle?+
What rocks look like russoite?+
What minerals are found with russoite?+
What kind of rock does russoite form in?+
What is russoite used for?+
Find russoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
