Ferri-winchite is a rare member of the amphibole supergroup characterized by its distinct blue to violet coloration. It is primarily found in metamorphic environments and alkaline igneous complexes as prismatic to fibrous crystals.
Is this ferri-winchite?
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-winchite with a known reference. Ferri-winchite 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 gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, fibrous aggregates.
Often confused with
Ferri-winchite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferri-winchite leaves greenish gray, Winchite leaves pale bluish gray.
How to tell apart: Streak differs, so Ferri-winchite leaves greenish gray, Richterite leaves white.
How to tell apart: Streak differs, so Ferri-winchite leaves greenish gray, Glaucophane leaves blue-gray.
Often found alongside ferri-winchite
Minerals reported to co-occur with ferri-winchite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- □NaCa(Mg₄Fe)Si₈O₂₂(OH)₂
- Mohs hardness
- 5.5
- Density
- 3.14 g/cm³
- Colors
- Streak
- Greenish gray
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, fibrous aggregates
- Cleavage
- Perfect in two directions
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In veins cutting pyroxene fenite in an alkaline igneous complex
Where rockhounds find ferri-winchite
Classic worldwide localities
- Khandivali, India
- Fen Complex, Norway
- Siberia, Russia
Field-hunting tip
Where it forms: In veins cutting pyroxene fenite in an alkaline igneous complex. If you start seeing calcite, quartz, pyrite in float, you are in the right ground. Typical habit: prismatic crystals, fibrous aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferri-winchite?+
Where is ferri-winchite found?+
What rocks look like ferri-winchite?+
What minerals are found with ferri-winchite?+
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Find ferri-winchite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
