Catapleiite
(Na,Ca,?)₃ZrSi₃O₉ · 2H₂O

     Over the years, Mont Saint-Hilaire has produced the largest crystallized specimens of catapleiite, making it the most sought
after species after sérandite.

PHYSICAL CHARACTERISTICS:

Color varies from tan to beige to pale gray to brown to colorless; very
   rarely pale yellow, pale orange, pink and very pale blue in small
   crystals.
Luster is vitreous; many crystals are coated with thin film that reduces
   the luster and gives some iridescence to the crystals.
Diaphaneity is transparent to translucent to opaque.
Crystal System is monoclinic (pseudo-orthorhombic, pseudo-
    hexagonal);B2/b
Crystal Habits include excellent hexagonal shaped plates, sometimes
   forming stacked rosettes; at least six twin laws are reported.
Cleavage {100} is perfect.
Fracture is conchoidal.
Hardness is 5.5
Specific Gravity is approximately 2.8 g/cm³
Streak is white.
Associated Minerals include aegirine, albite, amphiboles, analcime,
   ancylite, ankerite, astrophyllite, calcite, donnayite, fluorite, magnetite,
   natrolite, polylithionite, pyrochlore, rhodochrosite, siderite and
   sphalerite.
Distinguishing Features Pseudo-hexagonal paty crystal habit.
Origin: Named in 1851 from Greek kata, with and pleion, more, alluding
    to its association with a number of rare minerals.

CLASSIFICATION:

REFERENCES:
CanMin 16:195-198 (1978), MinRec 21:284 (1990),
Dana 8:1226-1227 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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