Ferri-ghoseite is a rare member of the amphibole group, specifically an iron-rich variant of the ghoseite species. It typically occurs as small prismatic crystals within metamorphic rock environments and is identified primarily through chemical analysis due to its visual similarity to other dark amphiboles.
Is this ferri-ghoseite?
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 ferri-ghoseite with a known reference. Ferri-ghoseite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferri-ghoseite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ferri-ghoseite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark brown, brownish-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Ferri-ghoseite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferri-ghoseite
Minerals reported to co-occur with ferri-ghoseite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(NaMg)(Mg₄Fe³⁺)Si₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.3-3.5 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect in Two Directions
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic
- Typical price
- $20-100 thumbnail
Where rockhounds find ferri-ghoseite
Classic worldwide localities
- Kutná Hora, Czech Republic
Field-hunting tip
Look in metamorphic country — that is the host setting where ferri-ghoseite typically forms. If you start seeing quartz, feldspar, biotite 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 ferri-ghoseite?+
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How much is ferri-ghoseite worth?+
What rocks look like ferri-ghoseite?+
What minerals are found with ferri-ghoseite?+
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Find ferri-ghoseite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
