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, 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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