Dawsonite

Dawsonite is a mineral composed of sodium aluminium carbonate hydroxide, chemical formula NaAlCO3(OH)2. It crystalizes in the orthorhombic crystal system. It is not mined for ore. It was discovered in 1874 during the construction of the Redpath Museum in a feldspathic dike on the campus of McGill University on the Island of Montreal, Canada. It is named after geologist Sir John William Dawson.
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(n.)
A hydrous carbonate of alumina and soda, occuring in white, bladed crustals.
  

General Information:
 Chemical Formula:
NaAl(CO3)(OH)2
 Composition:
(Molecular Weight = 126.99 gm)
Sodium 18.10 % Na
Aluminum 21.25 % Al
Hydrogen 0.79 % H 
Carbon 9.46 % C 
Oxygen 50.40 % O 
 Empirical Formula:
NaAl(CO3)(OH)
 Locality:
Feldspathic dike near McGill university, Montreal, Canada.
 Name Origin:
Named after the Canadian geologist, J. W. Dawson (1820-1899).
Physical Properties:
 Cleavage:
[110] Perfect
 Color:
colorless or white.
 Density:
2.4 - 2.44, Average = 2.42
 Diaphaniety:
Transparent
 Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Acicular - Occurs as needle-like crystals., Encrustations - Forms crust-like aggregates on mat rix.
 Hardness:
3 - Calcite
 Luminescence:
Fluorescent, Short UV=dull white.
 Luster:
Vitreous - Silky
 Streak:
white
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