Bosiite is a rare member of the tourmaline group, chemically distinct due to its high ferric iron content. It typically forms as prismatic crystals within pegmatite environments and is primarily sought after by advanced collectors of tourmaline species.
Is this bosiite?
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 bosiite with a known reference. Bosiite sits at Mohs 7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark brown, black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals.
Often confused with
Bosiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Bosiite leaves dark brown, Schorl leaves white.
How to tell apart: Streak differs, so Bosiite leaves dark brown, Foitite leaves grayish white.
How to tell apart: Streak differs, so Bosiite leaves dark brown, Olenite leaves white.
Often found alongside bosiite
Minerals reported to co-occur with bosiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaFe³⁺₃(Al₄Mg₂)Si₆O₁₈(BO₃)₃(OH)₃O
- Mohs hardness
- 7
- Density
- 3.23 g/cm³
- Colors
- Streak
- Dark brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a sulfide- and gold-bearing, sub-volcanic, hydrothermal quartz vein
Where rockhounds find bosiite
Classic worldwide localities
- Darasun gold deposit, Vershino-Darasunskiy, Transbaikal Krai, Eastern-Siberian Region, Russia
Field-hunting tip
Where it forms: In a sulfide- and gold-bearing, sub-volcanic, hydrothermal quartz vein. If you start seeing quartz, pyrite, oxy-dravite 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 bosiite?+
Where is bosiite found?+
What rocks look like bosiite?+
What minerals are found with bosiite?+
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Find bosiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
