Polylithionite
KLi₂AlSi₄O₁₀(F,OH)₂

     Polylithionite occurs at Mont Saint-Hilaire as superb pseudo- hexagonal crystals forming very attractive rosettes. Tainiolite is another closely related mica-group species ressembling polylithionite, however it does not fluoresce.

PHYSICAL CHARACTERISTICS:

Color varies from colorless to silvery; and in larger crystals from
   pale brown to pale yellow-brown.
Luster is pearly.
Diaphaneity is transparent to translucent or opaque for the larger
   crystals.
Crystal System is monoclinic; C2/m.
Crystal Habits include pseudohexagonal books, very thin and
   fairly loose lamellae.
Cleavage {001} is perfect.
Fracture is not apparent due to cleavage.
Hardness varies from 2 to 3
Specific Gravity is approximately 2.8g/cm³
Streak is white.
Associated Minerals include many minerals.
Distinguishing Features: Bright lemon-yellow fluorescence under SW,
   crystal habits.
Origin: Named in 1884 from the Greek polys, much, and lithium for its
   high lithium content.

CLASSIFICATION:

REFERENCES:
MinRec 21:330 (1990), Dana 8:1464 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

Legend