Willemite
Zn₂SiO₄

     Willemite is an extremely rare accessory mineral at MSH. It fluoresces brilliant green under SW and LW; it displays a strong dull green phosphorescence.

PHYSICAL CHARACTERISTICS:

Color ranges from beige, pale gray and pale blue on larger crystals
   and usually colorless on smaller crystals.
Luster is dull to greasy.
Diaphaneity is transparent in smaller crystals, translucent to
   opaque on larger crystals.
Crystal System is hexagonal; R3.
Crystal Habits include hexagonal prisms to 3mm terminated by
   small pyramids and pinacoids (exceptionally to 10cm).
Cleavage {001} and {110} are good.
Fracture is conchoidal to uneven.
Hardness is 5.5
Specific Gravity is approximately 4.1g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, analcime, ancylite,
   catapleiite, fluorite, mangan-neptunite, microcline, polylithionite,
   rhodochrosite and sphalerite.
Distinguishing Features: Crystal habit and its fluorescence.
Origin: Named in 1830 after William I (1772-1843), King of the
   Netherlands.

CLASSIFICATION:

REFERENCES:
MinRec 21:346 (1990), Dana 8:1022 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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