Osakaite is a rare zinc sulfate mineral that typically forms as delicate, transparent platy crystals within oxidized zones of zinc deposits. It is a secondary mineral commonly found encrusting other zinc species, requiring microscopic inspection for positive identification. It was first described from material found in the Osaka Prefecture, Japan.
Is this osakaite?
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 osakaite with a known reference. Osakaite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Osakaite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Osakaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals.
Often confused with
Osakaite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside osakaite
Minerals reported to co-occur with osakaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₄SO₄(OH)₆·5H₂O
- Mohs hardness
- 2
- Density
- 2.14 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals
- Cleavage
- Perfect On {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zinc Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find osakaite
Classic worldwide localities
- Osaka Prefecture, Japan
- Guanajuato, Mexico
- Katanga Province, DR Congo
Field-hunting tip
Look in oxidized zinc deposits country — that is the host setting where osakaite typically forms. If you start seeing smithsonite, hemimorphite, sphalerite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find osakaite on the map
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