Onoratoite is a rare antimony chloride mineral that typically forms as delicate, needle-like acicular crystals. It is primarily found within hydrothermal deposits associated with stibnite oxidation zones. Collectors value it for its unusual composition and rarity, often requiring magnification to appreciate its crystal structure.
Is this onoratoite?
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 onoratoite with a known reference. Onoratoite sits at Mohs 3, 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: white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular, bladed.
Often confused with
Onoratoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Onoratoite is noticeably harder (Mohs 3 vs. 2); streak differs, so Onoratoite leaves white, Stibnite leaves lead-gray; luster reads vitreous on Onoratoite and metallic, splendent on cleavage surfaces on Stibnite.
How to tell apart: Onoratoite is noticeably harder (Mohs 3 vs. 1-1.5); streak differs, so Onoratoite leaves white, Kermesite leaves brownish red; luster reads vitreous on Onoratoite and adamantine to semimetallic on Kermesite.
Often found alongside onoratoite
Minerals reported to co-occur with onoratoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Sb₈O₁₁Cl₂
- Mohs hardness
- 3
- Density
- 5.3 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Acicular, bladed
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of stibnite in an antimony deposit in highly silicified evaporites
Where rockhounds find onoratoite
Classic worldwide localities
- Cetine mine, 20 km southwest of Siena, Tuscany, Italy
Field-hunting tip
Where it forms: An oxidation product of stibnite in an antimony deposit in highly silicified evaporites. If you start seeing stibnite, stibiconite, cetineite in float, you are in the right ground. Typical habit: acicular, bladed. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify onoratoite?+
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Find onoratoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
