Zincaluminite is a rare secondary mineral typically found in the oxidized zones of zinc-rich base metal deposits. It is most commonly identified by its thin, platy to foliated white or pale blue crystal aggregates often forming crusts on other minerals like smithsonite.
Is this zincaluminite?
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 zincaluminite with a known reference. Zincaluminite 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. Zincaluminite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Zincaluminite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts, radial aggregates.
Often confused with
Zincaluminite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads pearly on Zincaluminite and dull on Hydrozincite.
How to tell apart: Smithsonite is the harder of the two (Mohs 4-4.5 vs. 2); luster reads pearly on Zincaluminite and vitreous on Smithsonite.
How to tell apart: Luster reads pearly on Zincaluminite and vitreous on Gypsum.
Often found alongside zincaluminite
Minerals reported to co-occur with zincaluminite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₄Al₂(OH)₁₂(SO₄)·3H₂O
- Mohs hardness
- 2
- Density
- 2.4-2.5 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Crusts, Radial Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Zinc Deposits
- Typical price
- $20-150 thumbnail, $100+ cabinet specimen
Where rockhounds find zincaluminite
Classic worldwide localities
- Lavrion District, Greece
- Tsumeb Mine, Namibia
- Cerro Gordo Mine, California, USA
Field-hunting tip
Look in oxidized zones of zinc deposits country — that is the host setting where zincaluminite typically forms. If you start seeing smithsonite, hydrozincite, aurichalcite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find zincaluminite on the map
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