Polylithionite

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Polylithionite crystals
Photo by Violet Anderson
© Royal Ontario Museum

Polylithionite crystals
© Doug Merson

Polylithionite crystals
© Gilles Haineault

KLiAlSi₁₀(F,OH)

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; 2/
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/cm
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:

Dana System
# 71.2.2b.8

Strunz Classification
# VIII/H.12-50

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

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
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Legend

Polylithionite crystals
© Doug Merson

Polylithionite crystals
© Stephan Wolfsried

Polylithionite crystals
© Stephan Wolfsried