Yofortierite is a rare manganese-bearing silicate mineral belonging to the sepiolite group. It typically appears as fibrous or needle-like white to pink aggregates within cavities of nepheline syenite rocks.
Is this yofortierite?
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 yofortierite with a known reference. Yofortierite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light pink.
- 3Read the lusterHold the specimen under a strong light. Luster: silky.
- 4Match the color rangeCompare against the expected color range: violet brown, light violet, pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, radial.
Often confused with
Yofortierite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Yofortierite leaves light pink, Sepiolite leaves white; luster reads silky on Yofortierite and dull on Sepiolite.
How to tell apart: Streak differs, so Yofortierite leaves light pink, Palygorskite leaves white; luster reads silky on Yofortierite and earthy to waxy on Palygorskite.
Often found alongside yofortierite
Minerals reported to co-occur with yofortierite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₅Si₈O₂₀(OH)₂·8-9H₂O
- Mohs hardness
- 2.5
- Density
- 2.18 g/cm³
- Colors
- Streak
- Light pink
- Luster
- Silky
- Transparency
- Transparent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, radial
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage hydrothermal mineral in pegmatite veins within nepheline syenite in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada)
Where rockhounds find yofortierite
Classic worldwide localities
- Mont Saint-Hilaire and in the Saint-Amable sill, near Varennes, Quebec, Canada
- Mt. Karnasurt, Lovozero massif, Russia
Field-hunting tip
Where it forms: A late-stage hydrothermal mineral in pegmatite veins within nepheline syenite in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada). If you start seeing analcime, sérandite, eudialyte in float, you are in the right ground. Typical habit: acicular, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify yofortierite?+
Where is yofortierite found?+
What rocks look like yofortierite?+
What minerals are found with yofortierite?+
What kind of rock does yofortierite form in?+
What is yofortierite used for?+
Find yofortierite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
