Glaucocerinite is a rare zinc-copper sulfate mineral typically found as secondary crusts or delicate platy aggregates in oxidized base-metal deposits. It is most famous for its occurrence in the historical mining district of Laurion, where it forms small, eye-catching blue coatings on other secondary minerals.
Is this glaucocerinite?
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 glaucocerinite with a known reference. Glaucocerinite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: bluish white.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy.
- 4Match the color rangeCompare against the expected color range: white, sky blue, gray, greenish, brownish.
- 5Look at form & habitCrystal system: trigonal. Typical habit: aggregates, nodular, radial.
Often confused with
Glaucocerinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Glaucocerinite leaves bluish white, Woodwardite leaves light blue; luster reads waxy on Glaucocerinite and pearly on Woodwardite.
How to tell apart: Hydrotalcite is the harder of the two (Mohs 2 vs. 1); streak differs, so Glaucocerinite leaves bluish white, Hydrotalcite leaves white; luster reads waxy on Glaucocerinite and satiny to greasy or waxy on Hydrotalcite.
How to tell apart: Streak differs, so Glaucocerinite leaves bluish white, Aurichalcite leaves light blue; luster reads waxy on Glaucocerinite and silky to pearly on Aurichalcite.
Often found alongside glaucocerinite
Minerals reported to co-occur with glaucocerinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₁-xAlx(SO₄)x/2(OH)₂·nH₂O (x<0.5, n>3x/2)
- Mohs hardness
- 1
- Density
- 2.4 g/cm³
- Streak
- Bluish white
- Luster
- Waxy
- Transparency
- Semitransparent
- Crystal system
- Trigonal
- Crystal habit
- Aggregates, nodular, radial
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral on museum specimens from a Cu–Zn sulfide deposit
Where rockhounds find glaucocerinite
Classic worldwide localities
- Laurium, Greece
Field-hunting tip
Where it forms: A rare secondary mineral on museum specimens from a Cu–Zn sulfide deposit. If you start seeing smithsonite, adamite, ktenasite in float, you are in the right ground. Typical habit: aggregates, nodular, radial. Train your eye for that shape before scanning the outcrop.
Common questions
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Find glaucocerinite on the map
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