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Hilairite crystal
Cynthia Peat sp.
Photo by Violet Anderson
© Royal Ontario Museum
Hilairite crystals
© Gilles Haineault
Hilairite crystals
© Doug Merson
NaZrSi · 3H
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; 32.
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/cm
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:
Dana System
# 59.2.3.1
Strunz Classification
# VIII/F.29-10
REFERENCES:
CanMin 12:237-240 (1974), MinRec 21:314 (1990), Dana 8:1229 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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Hilairite crystals
© Modris Baum
Hilairite crystals
© Doug Merson