Orthopinakiolite is a rare borate mineral primarily found in high-grade manganese skarn deposits. It typically forms dark, submetallic, elongated prismatic crystals that can be difficult to distinguish from related borates without mineralogical analysis.
Is this orthopinakiolite?
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 orthopinakiolite with a known reference. Orthopinakiolite 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. Orthopinakiolite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Orthopinakiolite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, elongated, fibrous to acicular aggregates.
Often confused with
Orthopinakiolite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside orthopinakiolite
Minerals reported to co-occur with orthopinakiolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Mn²⁺)₃Mn³⁺(BO₃)O₂
- Mohs hardness
- 6
- Density
- 4.15 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Elongated, Fibrous to Acicular Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese-rich Skarn Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find orthopinakiolite
Classic worldwide localities
- Langban, Sweden
- Jakobsberg, Sweden
- Harstigen, Sweden
Field-hunting tip
Look in manganese-rich skarn deposits country — that is the host setting where orthopinakiolite typically forms. If you start seeing hausmannite, magnetite, calcite in float, you are in the right ground. Field specimens usually show a prismatic crystals, elongated, fibrous to acicular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify orthopinakiolite?+
Where is orthopinakiolite found?+
How much is orthopinakiolite worth?+
What rocks look like orthopinakiolite?+
What minerals are found with orthopinakiolite?+
What kind of rock does orthopinakiolite form in?+
What is orthopinakiolite used for?+
Find orthopinakiolite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
