Bosoite is a silicate, typically colorless. It formed under low-temperature conditions during diagenesis of tuffaceous forearc sandstone and mudstone. Associated minerals include chibaite, quartz and calcite. It was first described from Arakawa, Minami-boso City, Chiba Prefecture, Japan.
Is this bosoite?
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 bosoite with a known reference. Bosoite sits at Mohs 6.5-7, 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: colorless.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: massive, crusts, or globular aggregates.
Often confused with
Bosoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Bosoite leaves white, Psilomelane leaves brownish black; luster reads vitreous on Bosoite and submetallic on Psilomelane.
How to tell apart: Streak differs, so Bosoite leaves white, Pyrolusite leaves black, bluish black; luster reads vitreous on Bosoite and metallic on Pyrolusite.
Often found alongside bosoite
Minerals reported to co-occur with bosoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂·nCₓH₂ₓ₊₂
- Mohs hardness
- 6.5-7
- Density
- 2.04 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Massive, crusts, or globular aggregates
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector
- Host rock
- Formed under low-temperature conditions during diagenesis of tuffaceous forearc sandstone and mudstone
Where rockhounds find bosoite
Classic worldwide localities
- Arakawa, Minami-boso City, Chiba Prefecture, Japan
Field-hunting tip
Where it forms: Formed under low-temperature conditions during diagenesis of tuffaceous forearc sandstone and mudstone. If you start seeing chibaite, quartz, calcite in float, you are in the right ground. Typical habit: massive, crusts, or globular aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bosoite?+
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What rocks look like bosoite?+
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Find bosoite on the map
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