Ferriandrosite-(Ce) is a rare member of the epidote group typically occurring as small, dark, prismatic crystals in manganese-rich deposits. It is structurally similar to androsite-(Ce) but distinguished by the dominance of iron at specific sites, requiring chemical analysis for definitive identification.
Is this ferriandrosite-(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 ferriandrosite-(ce) with a known reference. Ferriandrosite-(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. Ferriandrosite-(Ce) leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Ferriandrosite-(Ce) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Ferriandrosite-(Ce) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ferriandrosite-(Ce) leaves brown, Allanite leaves gray; luster reads vitreous on Ferriandrosite-(Ce) and submetallic on Allanite.
How to tell apart: Streak differs — Ferriandrosite-(Ce) leaves brown, Epidote leaves white.
Often found alongside ferriandrosite-(ce)
Minerals reported to co-occur with ferriandrosite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺CeAl₂Fe³⁺(SiO₄)(Si₂O₇)O(OH)
- Mohs hardness
- 6-6.5
- Density
- 4.2-4.4 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese-rich Metamorphic Rocks
- Typical price
- $50-300 per specimen depending on size and provenance
Where rockhounds find ferriandrosite-(ce)
Classic worldwide localities
- Varenche mine, Aosta Valley, Italy
- Ultevis, Norrbotten, Sweden
Field-hunting tip
Look in manganese-rich metamorphic rocks country — that is the host setting where ferriandrosite-(ce) typically forms. If you start seeing quartz, spessartine, rhodochrosite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferriandrosite-(ce)?+
Where is ferriandrosite-(ce) found?+
How much is ferriandrosite-(ce) worth?+
What rocks look like ferriandrosite-(ce)?+
What minerals are found with ferriandrosite-(ce)?+
What kind of rock does ferriandrosite-(ce) form in?+
What is ferriandrosite-(ce) used for?+
Find ferriandrosite-(ce) on the map
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