Bonazziite is a rare polymorph of arsenic sulfide that forms as a low-temperature product in volcanic fumaroles. It is structurally similar to realgar but can be distinguished by specific analytical methods; collectors typically find it as small, bright orange prismatic crystals in volcanic vent environments.

Hardness

1.5-2

Mohs

Luster

Resinous

Streak

Orange

Transparency

Translucent

mineralrareRealgar Group family

Bonazziite

Hardness: 1.5-2
Luster: Resinous
Streak: Orange
Transparency: Translucent

Is this bonazziite?

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 bonazziite with a known reference. Bonazziite 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. Bonazziite leaves a orange streak.
3
Read the luster
Hold the specimen under a strong light. Bonazziite typically shows a resinous luster.
4
Match the color range
Compare against the expected color range: orange, reddish-orange.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals.

Often confused with

Bonazziite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Realgar

Mohs 1.5-2

How to tell apart: Streak differs — Bonazziite leaves orange, Realgar leaves orange-red.

How to tell apart: Streak differs — Bonazziite leaves orange, Pararealgar leaves orange-yellow.

Compare →

Often found alongside bonazziite

Minerals reported to co-occur with bonazziite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: As₄S₄
Mohs hardness: 1.5-2
Density: 3.55 g/cm³
Colors: Orange Reddish-orange
Streak: Orange
Luster: Resinous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals
Cleavage: Distinct On {010}
Rarity: Rare
Uses: Collector
Host rock: Fumarolic Deposits
Typical price: $50-300 per specimen

Where rockhounds find bonazziite

Classic worldwide localities

Solfatara di Pozzuoli, Italy
Vulcano, Lipari Islands, Italy

Field-hunting tip

Look in fumarolic deposits country — that is the host setting where bonazziite typically forms. If you start seeing realgar, sulfur, gypsum in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bonazziite?+

Mohs hardness is 1.5-2. It typically shows a resinous luster. The streak is orange. Common colors include orange, reddish-orange.

Where is bonazziite found?+

Notable localities include Solfatara di Pozzuoli, Italy; Vulcano, Lipari Islands, Italy.

How much is bonazziite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is bonazziite safe to handle?+

It contains toxic constituents. Contains arsenic and sulfur; wash hands thoroughly after handling and avoid inhaling dust or vapors. Do not ingest or allow to come into contact with skin for extended periods. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like bonazziite?+

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

What minerals are found with bonazziite?+

Bonazziite commonly co-occurs with Realgar, Sulfur, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bonazziite form in?+

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

What is bonazziite used for?+

Bonazziite is used in collector.

Find bonazziite on the map

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