Gismondine
Ca₂Al₄Si₄O₁₆ · 9H₂O

     There are only a few confirmed specimens of gismondine from Mont Saint-Hilaire.

PHYSICAL CHARACTERISTICS:

Color is usually colorless to very pale pink.
Luster is vitreous.
Diaphaneity is transparent to translucent.
Crystal System is monoclinic; P2₁/c.
Crystal Habits include pseudo-octahedral to 1mm.
Cleavage {101} is distinct.
Fracture is conchoidal.
Hardness is 4.5
Specific Gravity is approximately 2.25 g/cm³.
Streak is white.
Associated Minerals include analcime.
Distinguishing Features: Crystal habit.
Origin: Named in 1817 after Carlo Giuseppe Gismondi (1762-1824),
   who first examined the mineral.

CLASSIFICATION:

REFERENCES:
MinRec 21:312 (1990), Dana 8:1661-1662 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

Legend