Ferroceladonite is a phyllosilicate mineral occurring primarily as earthy or micaceous coatings within the vesicles of volcanic rocks. It is visually distinguished from standard celadonite by its iron-dominant composition and is most frequently collected as an attractive green filling in basalt cavities.
Is this ferroceladonite?
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 ferroceladonite with a known reference. Ferroceladonite 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. Ferroceladonite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Ferroceladonite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: blue-green, green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, earthy, micaceous coatings.
Often confused with
Ferroceladonite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ferroceladonite leaves pale green, Celadonite leaves white.
How to tell apart: Streak differs — Ferroceladonite leaves pale green, Chlorite leaves white; luster reads dull on Ferroceladonite and pearly on Chlorite.
Often found alongside ferroceladonite
Minerals reported to co-occur with ferroceladonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KFe³⁺(Fe²⁺,Mg)(Si₄O₁₀)(OH)₂
- Mohs hardness
- 2
- Density
- 2.8-3.0 g/cm³
- Colors
- Streak
- Pale Green
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Earthy, Micaceous Coatings
- Cleavage
- Perfect Basal
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Amygdaloidal Basalt
- Typical price
- $10-50 per specimen
Where rockhounds find ferroceladonite
Classic worldwide localities
- Azores
- Iceland
- Italy
- India
Field-hunting tip
Look in amygdaloidal basalt country — that is the host setting where ferroceladonite typically forms. If you start seeing heulandite, stilbite, calcite in float, you are in the right ground. Field specimens usually show a massive, earthy, micaceous coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferroceladonite?+
Where is ferroceladonite found?+
How much is ferroceladonite worth?+
What rocks look like ferroceladonite?+
What minerals are found with ferroceladonite?+
What kind of rock does ferroceladonite form in?+
What is ferroceladonite used for?+
Find ferroceladonite on the map
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