Ferroaluminoceladonite is a rare phyllosilicate mineral belonging to the mica group. It typically occurs as fine-grained, earthy coatings or inclusions within volcanic rocks and hydrothermal veins. Collectors look for its characteristic soft green hues that distinguish it from more common clay or chlorite minerals.
Is this ferroaluminoceladonite?
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 ferroaluminoceladonite with a known reference. Ferroaluminoceladonite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: paler green.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: dark bluish green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals.
Often confused with
Ferroaluminoceladonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferroaluminoceladonite leaves paler green, Celadonite leaves greenish white; luster reads earthy on Ferroaluminoceladonite and dull on Celadonite.
How to tell apart: Streak differs, so Ferroaluminoceladonite leaves paler green, Glauconite leaves light green; luster reads earthy on Ferroaluminoceladonite and dull, glistening on Glauconite.
How to tell apart: Streak differs, so Ferroaluminoceladonite leaves paler green, Chlorite leaves white; luster reads earthy on Ferroaluminoceladonite and pearly on Chlorite.
Often found alongside ferroaluminoceladonite
Minerals reported to co-occur with ferroaluminoceladonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KFeAlSi₄O₁₀(OH)₂
- Mohs hardness
- 2-2.5
- Density
- 2.93 g/cm³
- Colors
- Dark bluish green
- Streak
- Paler green
- Luster
- Earthy
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In an altered crystal-vitric tuff intergrown with ferroceladonite
Where rockhounds find ferroaluminoceladonite
Classic worldwide localities
- Hokonui Hills, Southland, New (type locality)
Field-hunting tip
Where it forms: In an altered crystal-vitric tuff intergrown with ferroceladonite. If you start seeing quartz, calcite, zeolites 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 ferroaluminoceladonite?+
Where is ferroaluminoceladonite found?+
What rocks look like ferroaluminoceladonite?+
What minerals are found with ferroaluminoceladonite?+
What kind of rock does ferroaluminoceladonite form in?+
What is ferroaluminoceladonite used for?+
Find ferroaluminoceladonite on the map
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