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.
Is this bonazziite?
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 bonazziite with a known reference. Bonazziite sits at Mohs ~2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark orange.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: reddish orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Bonazziite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Bonazziite leaves dark orange, Realgar leaves red-orange to red.
How to tell apart: Bonazziite is noticeably harder (Mohs ~2.5 vs. 1-1.5); streak differs, so Bonazziite leaves dark orange, Pararealgar leaves bright yellow; luster reads resinous on Bonazziite and vitreous to resinous on Pararealgar.
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
- ~2.5
- Density
- 3.542 g/cm³
- Colors
- Streak
- Dark orange
- Luster
- Resinous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Low-temperature hydrothermal mineral probably formed while the system had direct involvement of magmatic volatiles
Where rockhounds find bonazziite
Classic worldwide localities
- Khaidarkan Sb-Hg deposit, south of Fergana Valley, Alai Range, Osh Oblast, Kyrgyzstan
Field-hunting tip
Where it forms: Low-temperature hydrothermal mineral probably formed while the system had direct involvement of magmatic volatiles. If you start seeing realgar, sulfur, wakabayashilite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bonazziite?+
Where is bonazziite found?+
Is bonazziite safe to handle?+
What rocks look like bonazziite?+
What minerals are found with bonazziite?+
What kind of rock does bonazziite form in?+
What is bonazziite used for?+
Find bonazziite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
