Jimboite is a rare manganese borate mineral that typically forms as small, prismatic crystals within manganese-rich contact metamorphic environments. Collectors primarily find it in specific high-grade manganese deposits, most notably in Japan where it was first discovered.
Is this jimboite?
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 jimboite with a known reference. Jimboite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Jimboite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Jimboite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals.
Often confused with
Jimboite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside jimboite
Minerals reported to co-occur with jimboite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₃(BO₃)₂
- Mohs hardness
- 6
- Density
- 3.55 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese-rich Metamorphic Deposits
- Typical price
- $50-300+ per specimen
Where rockhounds find jimboite
Classic worldwide localities
- Kaso mine, Tochigi Prefecture, Japan
- Fuka mine, Okayama Prefecture, Japan
- Cerchiara mine, Liguria, Italy
Field-hunting tip
Look in manganese-rich metamorphic deposits country — that is the host setting where jimboite typically forms. If you start seeing jacobsite, hausmannite, alleghanyite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find jimboite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
