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Dawsonite crystals - click for larger pic
Dawsonite crystals
Photo by Doug Merson
© Doug Merson

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Dawsonite
NaAl(CO3)(OH)2

     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/cm3.
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
¤¤¤

PE
--

AP
--

MX
--

SS
¤¤

MC
--

HF
¤¤

BR
--

SX
--

FR
--

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