Zircophyllite is a rare member of the astrophyllite group, primarily distinguished by its high zirconium content and distinct triclinic symmetry. Collectors typically find it as thin, bladed, or platy bronze-brown crystals within alkaline pegmatites, often associated with other rare earth silicate minerals.
Is this zircophyllite?
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 zircophyllite with a known reference. Zircophyllite sits at Mohs 4-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: dark brown, black, black brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: micaceous, platy.
Often confused with
Zircophyllite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Zircophyllite is noticeably harder (Mohs 4-4.5 vs. 3); streak differs, so Zircophyllite leaves pale brown, Astrophyllite leaves golden; luster reads vitreous to adamantine on Zircophyllite and submetallic, pearly, greasy on Astrophyllite.
How to tell apart: Streak differs, so Zircophyllite leaves pale brown, Kupletskite leaves brown.
Often found alongside zircophyllite
Minerals reported to co-occur with zircophyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂NaFe₇Zr₂(Si₄O₁₂)₂O₂(OH)₄F
- Mohs hardness
- 4-4.5
- Density
- 3.34 g/cm³
- Streak
- Pale brown
- Luster
- Vitreous to adamantine
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Micaceous, platy
- Cleavage
- {001}, perfect
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In the natrolite zone of alkalic pegmatites
Where rockhounds find zircophyllite
Classic worldwide localities
- Korgeredaba alkaline massif, Sangilen Upland, southeastern Tuva, Russia
Field-hunting tip
Where it forms: In the natrolite zone of alkalic pegmatites. If you start seeing aegirine-augite, leucophanite, fluorite in float, you are in the right ground. Typical habit: micaceous, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify zircophyllite?+
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What rocks look like zircophyllite?+
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Find zircophyllite on the map
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