General Information:
Chemical Formula:
NaCa2Al5Si5O20·6(H2O)
Composition:
(Molecular Weight = 806.56 gm)
Sodium 2.85 % Na
Calcium 9.94 % Ca
Aluminum 16.73 % Al
Silicon 17.41 % Si
Hydrogen 1.50 % H
Oxygen 51.58 % O
Empirical Formula:
NaCa2Al5Si5O20·6(H2O)
Environment:
Found in cavities in lava and in amygdaloidal igneous rocks.
IMA Status:
Approved IMA
Locality:
Kilpatrick Hills, Bunbarton, Scotland.
Name Origin:
Named after the Scottish chemist, T. Thomson (1773-1852).
Physical Properties:
Cleavage:
[101] Perfect, [100] Good
Color:
colorless, greenish, yellow, white, or pink.
Density:
2.3 - 2.4, Average = 2.34
Diaphaniety:
Transparent to translucent
Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Fibrous - Crystals made up of fibers., Spherical - Spherical, rounded aggregates.
Hardness:
5-5.5 - Apatite-Knife Blade
Luminescence:
None.
Luster:
Vitreous (Glassy)
Streak:
white
More details...