Aluminoceladonite is a member of the mica group often found as a secondary mineral resulting from the hydrothermal alteration of volcanic rocks. It is noted for its distinctive blue-green color and micaceous, earthy habit, often forming crusts or coatings within vugs and fractures.
Is this aluminoceladonite?
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 aluminoceladonite with a known reference. Aluminoceladonite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: blue, green, blue-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, micaceous, earthy, or as fibrous aggregates.
Often confused with
Aluminoceladonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Aluminoceladonite leaves white, Celadonite leaves greenish white; luster reads pearly on Aluminoceladonite and dull on Celadonite.
How to tell apart: Streak differs, so Aluminoceladonite leaves white, Glauconite leaves light green; luster reads pearly on Aluminoceladonite and dull, glistening on Glauconite.
How to tell apart: Luster reads pearly on Aluminoceladonite and earthy on Illite.
Often found alongside aluminoceladonite
Minerals reported to co-occur with aluminoceladonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KAl(Mg,Fe²⁺)Si₄O₁₀(OH)₂
- Mohs hardness
- 2
- Density
- 2.8-2.9 g/cm³
- Colors
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive, micaceous, earthy, or as fibrous aggregates
- Cleavage
- Perfect basal
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- hydrothermal veins, altered volcanic rocks
Where rockhounds find aluminoceladonite
Classic worldwide localities
- Wiesmath ant Frohsdorf, Austria (type locality)
Field-hunting tip
Where it forms: hydrothermal veins, altered volcanic rocks. If you start seeing quartz, calcite, chlorite in float, you are in the right ground. Typical habit: massive, micaceous, earthy, or as fibrous aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify aluminoceladonite?+
Where is aluminoceladonite found?+
What rocks look like aluminoceladonite?+
What minerals are found with aluminoceladonite?+
What kind of rock does aluminoceladonite form in?+
What is aluminoceladonite used for?+
Find aluminoceladonite on the map
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