Sonolite is a rare manganese silicate member of the humite group, typically found in metamorphosed manganese deposits. It is best identified by its characteristic bright yellow fluorescence under UV light, which helps distinguish it from other chemically similar humite group minerals.
Is this sonolite?
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 sonolite with a known reference. Sonolite sits at Mohs 5.5, 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: dull to vitreous.
- 4Match the color rangeCompare against the expected color range: dark brown, dark reddish brown, pink brown, reddish orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular to massive, rarely as distinct tabular crystals.
Often confused with
Sonolite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Sonolite leaves white, Chondrodite leaves gray; luster reads dull to vitreous on Sonolite and vitreous to resinous on Chondrodite.
How to tell apart: Luster reads dull to vitreous on Sonolite and vitreous on Humite.
How to tell apart: Luster reads dull to vitreous on Sonolite and vitreous on Clinohumite.
Often found alongside sonolite
Minerals reported to co-occur with sonolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₉(SiO₄)₄(OH)₂
- Mohs hardness
- 5.5
- Density
- 3.82-4.00 g/cm³
- Streak
- White
- Luster
- Dull to vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Granular to massive, rarely as distinct tabular crystals
- Cleavage
- Indistinct
- Fluorescence
- Bright yellow under SW and LW UV
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In metamorphosed manganese-rich deposits
Where rockhounds find sonolite
Classic worldwide localities
- Franklin and Sterling Hill, Ogdensburg, Sussex Co., New Jersey, and at Bald Knob, near Sparta, Alleghany Co., North Carolina, USA
- Sono mine, Kyoto Prefecture, Japan
- Hanawa mine, Iwate Prefecture, Japan
- Hokkejino mine, Kyoto Prefecture, Japan
- Kuratomi mine, Oita Prefecture, Japan
- A number of other places in Japan
Field-hunting tip
Where it forms: In metamorphosed manganese-rich deposits. If you start seeing rhodochrosite, galaxite, pyrochroite in float, you are in the right ground. Typical habit: granular to massive, rarely as distinct tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find sonolite on the map
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