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Dawsonite crystals
Photo by Doug Merson
© Doug Merson
NaAl(CO)(OH)
Dawsonite is relatively rare at Mont Saint-Hilaire. It occurs more frequently on the other Monteregian Hills.
PHYSICAL CHARACTERISTICS:
Color is usually colorless to white.
Luster is vitreous to silky.
Diaphaneity is transparent to translucent.
Crystal System is orthorhombic; Imam
Crystal Habits include embedded crystalline masses and rarely
as sharp, striated prismatic crystals to 35mm.
Cleavage {110} is perfect.
Fracture is (??).
Hardness is 3.
Specific Gravity is approximately 2.44 g/cm
Streak is white.
Associated Minerals include albite, analcime, calcite, fluorite,
galena, gonnardite, marcasite, molybdenite, natrolite, paranatrolite,
phlogopite, pyrite, quartz, rutile, sabinaite, siderite, sodalite,
sphalerite and synchysite.
Distinguishing Features: Crystal habit and striated aspect.
Origin: Named in 1874 after Sir John William Dawson (1820-1899),
Canadian geologist and principal of McGill University in Montreal,
Canada.
CLASSIFICATION:
Dana System
# 16a.3.8.1
Strunz Classification
# V/C.2-2
REFERENCES:
MinRec 21:305 (1990), Dana 8:492-493 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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