Catapleiite typically forms as distinctive pseudohexagonal tabular crystals, often occurring in alkaline igneous environments. It is highly sought after by collectors of micro-minerals for its clean, often glass-like crystal shapes. It is most notably found in the famous nepheline syenite pegmatites of Mont Saint-Hilaire.
Is this catapleiite?
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 catapleiite with a known reference. Catapleiite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white to pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: weakly vitreous or dull.
- 4Match the color rangeCompare against the expected color range: colorless, blue, brown, yellow, yellow brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy, pseudo hexagonal.
Often confused with
Catapleiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads weakly vitreous or dull on Catapleiite and vitreous to dull on Eudialyte.
How to tell apart: Zircon is the harder of the two (Mohs 7.5 vs. 5.5-6); luster reads weakly vitreous or dull on Catapleiite and vitreous to adamantine; greasy when metamict on Zircon.
Often found alongside catapleiite
Minerals reported to co-occur with catapleiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂ZrSi₃O₉·2H₂O
- Mohs hardness
- 5.5-6
- Density
- 2.65-2.9 g/cm³
- Streak
- White to pale yellow
- Luster
- Weakly vitreous or dull
- Transparency
- Transparent, translucent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Platy, pseudo hexagonal
- Cleavage
- {100}, perfect; {101} and {102}, imperfect
- Fluorescence
- Green under SW and LW UV
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- In syenites and nepheline syenites; in pegmatites, typically the result of metasomatic alteration of eudialyte
Where rockhounds find catapleiite
Classic worldwide localities
- Magnet Cove, Hot Springs Co., and from Granite Mountain, near Little Rock, Pulaski Co., Arkansas, USA
- Rocky Boy stock, Bearpaw Mountains, Hill Co., Montana, USA
- Wind Mountain, Otero Co., New Mexico, USA
- Låven Island and other localities around the Langesundsfjord, and at Bratthagen, Norway
- Mont Saint-Hilaire, from the Miron quarry, Montreal, and near Saint-Amable, Quebec, Canada
- Ice River valley, 25 km south of Field, British Columbia, Canada
Field-hunting tip
Where it forms: In syenites and nepheline syenites; in pegmatites, typically the result of metasomatic alteration of eudialyte. If you start seeing zircon, leucophanite, rinkite in float, you are in the right ground. Typical habit: platy, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify catapleiite?+
Where is catapleiite found?+
What rocks look like catapleiite?+
What minerals are found with catapleiite?+
What kind of rock does catapleiite form in?+
What is catapleiite used for?+
Find catapleiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
