Ferripyrophyllite is a rare phyllosilicate mineral that represents the iron-dominant analog of pyrophyllite. It typically occurs as soft, pearly, foliated masses or coatings in metamorphosed, iron-rich sedimentary environments, often requiring X-ray diffraction for definitive identification due to its similarity to other clay minerals.
Is this ferripyrophyllite?
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 ferripyrophyllite with a known reference. Ferripyrophyllite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: brownish yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: scaly.
Often confused with
Ferripyrophyllite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferripyrophyllite leaves light yellow, Pyrophyllite leaves white.
How to tell apart: Streak differs, so Ferripyrophyllite leaves light yellow, Talc leaves white.
How to tell apart: Streak differs, so Ferripyrophyllite leaves light yellow, Celadonite leaves greenish white; luster reads pearly on Ferripyrophyllite and dull on Celadonite.
Often found alongside ferripyrophyllite
Minerals reported to co-occur with ferripyrophyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeSi₂O₅(OH)
- Mohs hardness
- 1.5-2
- Density
- 2.97-3.01 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Scaly
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Found on museum specimens
Where rockhounds find ferripyrophyllite
Classic worldwide localities
- Strassenschacht hematite deposit, south of Eibenstock, Saxony, Germany
- Tulagai Pb-Cu deposit, near Akchatau, Kazakhstan
Field-hunting tip
Where it forms: Found on museum specimens. If you start seeing quartz, hematite, magnetite in float, you are in the right ground. Typical habit: scaly. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferripyrophyllite?+
Where is ferripyrophyllite found?+
What rocks look like ferripyrophyllite?+
What minerals are found with ferripyrophyllite?+
What kind of rock does ferripyrophyllite form in?+
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Find ferripyrophyllite on the map
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