Ferrowyllieite is a rare phosphate mineral primarily found in complex granite pegmatites. It typically appears as green to yellow-green granular or crystalline masses and is often identified via chemical analysis due to its similarity to other members of the wyllieite group.
Is this ferrowyllieite?
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 ferrowyllieite with a known reference. Ferrowyllieite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferrowyllieite leaves a dirty olive-green streak.
- 3Read the lusterHold the specimen under a strong light. Ferrowyllieite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive, prismatic crystals.
Often confused with
Ferrowyllieite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferrowyllieite leaves dirty olive-green, Wyllieite leaves white; luster reads submetallic on Ferrowyllieite and vitreous on Wyllieite.
How to tell apart: Streak differs, so Ferrowyllieite leaves dirty olive-green, Triplite leaves white; luster reads submetallic on Ferrowyllieite and vitreous on Triplite.
Often found alongside ferrowyllieite
Minerals reported to co-occur with ferrowyllieite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,Ca,Mn²⁺)₂(Fe²⁺,Mn²⁺)(Fe²⁺,Fe³⁺,Mg)Al(PO₄)₃
- Mohs hardness
- 4-5
- Density
- 3.8-3.9 g/cm³
- Colors
- Streak
- Dirty Olive-green
- Luster
- Submetallic
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, Massive, Prismatic Crystals
- Cleavage
- Perfect On {010}; On {101}, Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
Where rockhounds find ferrowyllieite
Classic worldwide localities
- Palmeira pegmatite, Brazil
- Tip Top mine, South Dakota, USA
- Norrö, Sweden
Field-hunting tip
Look in granite pegmatites country, the host setting where ferrowyllieite typically forms. If you start seeing triphylite, albite, quartz in float, you are in the right ground. Field specimens usually show a granular, massive, prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrowyllieite?+
Where is ferrowyllieite found?+
What rocks look like ferrowyllieite?+
What minerals are found with ferrowyllieite?+
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What is ferrowyllieite used for?+
Find ferrowyllieite on the map
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