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 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: white, bluish white, light blue.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: microscopic crystals.
Often confused with
Zincaluminite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Smithsonite is the harder of the two (Mohs 4-4.5 vs. 2.5-3); luster reads pearly on Zincaluminite and vitreous, may be pearly on Smithsonite.
How to tell apart: Luster reads pearly on Zincaluminite and subvitreous, pearly on {010} cleavages, silky if fibrous 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
- 2.5-3
- Density
- 2.26 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Hexagonal
- Crystal habit
- Microscopic crystals
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of a Ag–Zn mine
Where rockhounds find zincaluminite
Classic worldwide localities
- Laurium, at the Kamariza mine, Greece
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of a Ag–Zn mine. If you start seeing smithsonite, aurichalcite, hydrozincite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify zincaluminite?+
Where is zincaluminite found?+
Is zincaluminite safe to handle?+
What rocks look like zincaluminite?+
What minerals are found with zincaluminite?+
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Find zincaluminite on the map
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