Leifite
Na₂(Si,Al,Be)₇(O,OH,F)₁₄

Mont Saint-Hilaire has provided the world's finest and largest crystals of leifite since the beginning of its quarrying operations.

PHYSICAL CHARACTERISTICS:

Color is colorless to pure white, with pale violet surfaces on larger
   aggregates.
Luster is vitreous to silky.
Diaphaneity is transparent to translucent.
Crystal System is hexagonal; P3m1.
Crystal Habits include fibrous or acicular, spherical aggregates,
   simple hexagonal prisms terminated by pinacoid.
Cleavage {100} is distinct.
Fracture uneven to splintery.
Hardness is 6
Specific Gravity is approximately 2.6g/cm³
Streak is white.
Associated Minerals include aegirine, albite, ancylite, catapleiite,
   fluorite, genthelvite, mangan-neptunite, microcline, monteregianite,
   natrolite, polylithionite and rhodochrosite.
Distinguishing Features: Prismatic crystal habit.
Origin: Named in 1915 for the tenth-century Norse mariner and
   explorer Leif Ericson.