Ferrocarpholite is a distinct iron-rich member of the carpholite group found primarily in high-pressure metamorphic terranes. It is most easily identified by its characteristic fibrous or needle-like crystal habits that often form radiating sheaves or bundles within its host rock.
Is this ferrocarpholite?
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 ferrocarpholite with a known reference. Ferrocarpholite sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: silky.
- 4Match the color rangeCompare against the expected color range: gray green, dark green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, acicular, radiating clusters.
Often confused with
Ferrocarpholite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferrocarpholite leaves greenish white, Carpholite leaves white.
How to tell apart: Streak differs, so Ferrocarpholite leaves greenish white, Actinolite leaves white; luster reads silky on Ferrocarpholite and vitreous, silky on Actinolite.
How to tell apart: Streak differs, so Ferrocarpholite leaves greenish white, Tremolite leaves white; luster reads silky on Ferrocarpholite and vitreous on Tremolite.
Often found alongside ferrocarpholite
Minerals reported to co-occur with ferrocarpholite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺Al₂Si₂O₆(OH)₄
- Mohs hardness
- 5.5
- Density
- 3.04 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Silky
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, acicular, radiating clusters
- Cleavage
- Perfect on {010}, indistinct on {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In quartz veins in blueschists of low metamorphic grade, formed from felsic tuffs at about 250 ° C and 3 kbar
Where rockhounds find ferrocarpholite
Classic worldwide localities
- Diahot region, New Caledonia
- Colle Ciarbonet, Piedmont, Italy
- Vanoise massif, Savoie, and Pic du Pelvat, Haute-Ubaye district, Alpes-de-Haute Provence, France
- Ruwi, Oman
Field-hunting tip
Where it forms: In quartz veins in blueschists of low metamorphic grade, formed from felsic tuffs at about 250 ° C and 3 kbar. If you start seeing quartz, glaucophane, lawsonite in float, you are in the right ground. Typical habit: fibrous, acicular, radiating clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrocarpholite?+
Where is ferrocarpholite found?+
What rocks look like ferrocarpholite?+
What minerals are found with ferrocarpholite?+
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What is ferrocarpholite used for?+
Find ferrocarpholite on the map
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