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.

Hardness

1.5-2

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

Russoite

Hardness: 1.5-2
Luster: Vitreous
Streak: White
Transparency: Translucent

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Is this russoite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try 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.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Russoite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Russoite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal 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.

How to tell apart: Luster reads vitreous on Russoite and resinous to subadamantine on Senarmontite.

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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: NH₄Cl(As,Sb)₄O₆
Mohs hardness: 1.5-2
Density: 2.89 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Hexagonal
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Fumarolic Deposits

Where rockhounds find russoite

Classic worldwide localities

La Fossa crater, Vulcano, Aeolian Islands, Italy

Field-hunting tip

Look in fumarolic deposits country, the host setting where russoite typically forms. If you start seeing arsenolite, senarmontite, realgar in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify russoite?+

Mohs hardness is 1.5-2. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is russoite found?+

Notable localities include La Fossa crater, Vulcano, Aeolian Islands, Italy.

Is russoite safe to handle?+

It contains toxic constituents. Contains arsenic and antimony. Handle with care, wash hands after handling, avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like russoite?+

Russoite is most often confused with Arsenolite, Senarmontite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with russoite?+

Russoite commonly co-occurs with Arsenolite, Senarmontite, Realgar, Sal-ammoniac. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does russoite form in?+

Russoite typically forms in fumarolic deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is russoite used for?+

Russoite is used in collector.

Find russoite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.