Ferriakasakaite-(La) is an extremely rare member of the epidote supergroup characterized by its high lanthanum content. It typically occurs as small, dark anhedral grains embedded within metamorphic rocks in specialized geological environments. Collectors primarily seek this mineral for its significance in rare-earth element mineralogy.
Is this ferriakasakaite-(la)?
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-(la) with a known reference. Ferriakasakaite-(La) sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferriakasakaite-(La) leaves a brownish streak.
- 3Read the lusterHold the specimen under a strong light. Ferriakasakaite-(La) typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral grains.
Often confused with
Ferriakasakaite-(La) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ferriakasakaite-(La) leaves brownish, Epidote leaves white; luster reads submetallic on Ferriakasakaite-(La) and vitreous on Epidote.
How to tell apart: Streak differs — Ferriakasakaite-(La) leaves brownish, Allanite leaves gray.
Often found alongside ferriakasakaite-(la)
Minerals reported to co-occur with ferriakasakaite-(la). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaLaFe³⁺AlMn²⁺(Si₂O₇)(SiO₄)O(OH)
- Mohs hardness
- 6-7
- Density
- 4.15 g/cm³
- Colors
- Streak
- Brownish
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Rocks
- Typical price
- $50-300 per specimen depending on size and provenance
Where rockhounds find ferriakasakaite-(la)
Classic worldwide localities
- Fukuokamachi, Japan
- Shikoku, Japan
Field-hunting tip
Look in metamorphic rocks country — that is the host setting where ferriakasakaite-(la) typically forms. If you start seeing quartz, albite, muscovite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferriakasakaite-(la)?+
Where is ferriakasakaite-(la) found?+
How much is ferriakasakaite-(la) worth?+
What rocks look like ferriakasakaite-(la)?+
What minerals are found with ferriakasakaite-(la)?+
What kind of rock does ferriakasakaite-(la) form in?+
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Find ferriakasakaite-(la) on the map
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