Winchite is a rare member of the amphibole group, typically found in manganese-rich metamorphic environments. It is most recognized for its characteristic lavender to blue-violet color, occurring as prismatic crystals or fibrous aggregates.
Is this 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 winchite with a known reference. 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: pale bluish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: cobalt blue, violet blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, fibrous, massive.
Often confused with
Winchite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Winchite leaves pale bluish gray, Tremolite leaves white.
How to tell apart: Streak differs, so Winchite leaves pale bluish gray, Actinolite leaves white.
How to tell apart: Streak differs, so Winchite leaves pale bluish gray, Glaucophane leaves blue-gray.
Often found alongside winchite
Minerals reported to co-occur with winchite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- □NaCa(Mg₄Al)Si₈O₂₂(OH)₂
- Mohs hardness
- 5.5
- Density
- 2.97-3.175 g/cm³
- Colors
- Cobalt blueViolet blue
- Streak
- Pale bluish gray
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, fibrous, massive
- Cleavage
- Perfect on {110}, intersecting at ~56° and ~124°; partings on {100}, {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In schists with low-grade metamorphosed manganese deposits; in metabasalts of the jadeite-glaucophane and amphibolite-eclogite facies; in manganiferous cherts that have undergone blueschist facies metamorphism
Where rockhounds find winchite
Classic worldwide localities
- Ward Creek, Cazadero, Sonoma Co., California, USA
- Kajlidongri mine, Jhabua district, Madhya Pradesh, India
- El Valle del Espiritu Santo, Margarita Island, Venezuela
- Praborna mine, near St. Marcel, Val d'Aosta, Italy
- North of Kitami City, Hokkaido, Japan
Field-hunting tip
Where it forms: In schists with low-grade metamorphosed manganese deposits; in metabasalts of the jadeite-glaucophane and amphibolite-eclogite facies; in manganiferous cherts that have undergone blueschist facies metamorphism. If you start seeing calcite, microcline, diopside in float, you are in the right ground. Typical habit: prismatic crystals, fibrous, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find winchite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
