Hilairite (Type Locality)
Na₂ZrSi₃O₉ · 3H₂O

     Hilairite was described as a new species from Mont Saint-Hilaire in 1974. It had originally been designated as UK #20.

PHYSICAL CHARACTERISTICS:

Color is usually pale to dark brown, and pink.
Luster is vitreous to waxy to porcelaneous.
Diaphaneity is transparent to opaque.
Crystal System is hexagonal; R32.
Crystal Habits include short to elongated trigonal or hexagonal
   prisms terminated by the rhombohedron to 4mm; most crystals
   are doubly terminated and twinning is frequent.
Cleavage none observed.
Fracture is concohidal.
Hardness is >4.
Specific Gravity is approximately 2.72 g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, analcime, ancylite,
   calcite, catapleiite, chlorite group, elpidite, epididymite, eudialyte,
   fluorite, gaidonnayite, galena, goethite, mangan-neptunite,
   microcline, natrolite, nenadkevichite, polylithionite, pyrite, quartz,
   rhodochrosite, sphalerite and zircon.
Distinguishing Features: Crystal habit, color and association
   with gaidonnayite.
Origin: Named in 1974 after its discovery locality, at Mont Saint-
   Hilaire, Rouville County, Quebec, Canada.

CLASSIFICATION:

REFERENCES:
CanMin 12:237-240 (1974), MinRec 21:314 (1990), Dana 8:1229 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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