Pinakiolite is a rare borate mineral typically found in metamorphosed manganese deposits. It forms dark, prismatic crystals that are often heavily striated, and it is most famous for its occurrences in the classic mining districts of Sweden.
Is this pinakiolite?
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 pinakiolite with a known reference. Pinakiolite 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. Pinakiolite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Pinakiolite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, dark brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, massive.
Often confused with
Pinakiolite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Pinakiolite is noticeably harder (Mohs 6 vs. 5); streak differs — Pinakiolite leaves brown, Ludwigite leaves black.
How to tell apart: Pinakiolite is noticeably harder (Mohs 6 vs. 5); streak differs — Pinakiolite leaves brown, Vonsenite leaves black.
Often found alongside pinakiolite
Minerals reported to co-occur with pinakiolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃Mn²⁺O₂(BO₃)
- Mohs hardness
- 6
- Density
- 4.15 g/cm³
- Colors
- Streak
- Brown
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Manganese Ore Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find pinakiolite
Classic worldwide localities
- Långban, Sweden
- Nordmark, Sweden
- Jakobsberg, Sweden
Field-hunting tip
Look in metamorphosed manganese ore deposits country — that is the host setting where pinakiolite typically forms. If you start seeing hausmannite, braunite, dolomite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find pinakiolite on the map
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