Olmiite is a highly sought-after rare silicate mineral primarily found in the Kalahari Manganese Field. It typically occurs as beautiful, salmon-pink to brown crystalline clusters or drusy coatings on manganese ore specimens. It is easily confused with poldervaartite and often requires chemical testing or XRD for definitive identification.
Is this olmiite?
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 olmiite with a known reference. Olmiite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Olmiite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Olmiite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, brown, white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: bladed, drusy, or radiating crystal aggregates.
Often confused with
Olmiite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside olmiite
Minerals reported to co-occur with olmiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMn(SiO₄)(OH)₂
- Mohs hardness
- 5
- Density
- 3.16 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Bladed, Drusy, Or Radiating Crystal Aggregates
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese Deposits in Sedimentary Formations
- Typical price
- $50-500 thumbnail, $200-1500 cabinet
Where rockhounds find olmiite
Classic worldwide localities
- N'Chwaning Mines, Kalahari Manganese Field, South Africa
Field-hunting tip
Look in manganese deposits in sedimentary formations country — that is the host setting where olmiite typically forms. If you start seeing calcite, bultfonteinite, sturmanite in float, you are in the right ground. Field specimens usually show a bladed, drusy, or radiating crystal aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find olmiite on the map
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