Ferriakasakaite-(Ce) is a rare member of the epidote supergroup found primarily in metamorphosed manganese-rich rocks. Collectors will typically identify this species through professional X-ray diffraction or chemical analysis due to its visual similarity to dark, massive members of the allanite subgroup.
Is this ferriakasakaite-(ce)?
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 ferriakasakaite-(ce) with a known reference. Ferriakasakaite-(Ce) sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferriakasakaite-(Ce) leaves a brownish black streak.
- 3Read the lusterHold the specimen under a strong light. Ferriakasakaite-(Ce) typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral to subhedral grains.
Often confused with
Ferriakasakaite-(Ce) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ferriakasakaite-(Ce) leaves brownish black, Epidote leaves white; luster reads submetallic on Ferriakasakaite-(Ce) and vitreous on Epidote.
How to tell apart: Streak differs — Ferriakasakaite-(Ce) leaves brownish black, Allanite leaves gray.
Often found alongside ferriakasakaite-(ce)
Minerals reported to co-occur with ferriakasakaite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCeFe³⁺AlMn²⁺(Si₂O₇)(SiO₄)O(OH)
- Mohs hardness
- 6-6.5
- Density
- 4.15 g/cm³
- Streak
- Brownish Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral to Subhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Rocks
- Typical price
- $50-200 for micro-mounts
Where rockhounds find ferriakasakaite-(ce)
Classic worldwide localities
- Japan
- Italy
Field-hunting tip
Look in metamorphic rocks country — that is the host setting where ferriakasakaite-(ce) typically forms. If you start seeing quartz, albite, microcline in float, you are in the right ground. Field specimens usually show a anhedral to subhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferriakasakaite-(ce)?+
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What rocks look like ferriakasakaite-(ce)?+
What minerals are found with ferriakasakaite-(ce)?+
What kind of rock does ferriakasakaite-(ce) form in?+
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Find ferriakasakaite-(ce) on the map
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