General Information:
Chemical Formula:NaCa2Al5Si5O20·6(H2O)
Composition:(Molecular Weight = 806.56 gm)Sodium 2.85 %
NaCalcium 9.94 %
CaAluminum 16.73 %
AlSilicon 17.41 %
SiHydrogen 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
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