General Information:
Chemical Formula:
Na2Ca5Al12Si20O64·27(H2O)
Composition:
(Molecular Weight = 2,642.23 gm)
Sodium 1.74 % Na
Calcium 7.58 % Ca
Aluminum 12.25 % Al
Silicon 21.26 % Si
Hydrogen 2.06 % H
Oxygen 55.10 % O
Empirical Formula:
Na2Ca5Al12Si20O64·27(H2O)
IMA Status:
Approved IMA 1962
Name Origin:
Named after its locality in Garron Plateau, Northern Ireland.
Physical Properties:
Cleavage:
[???] Good, [???] Good
Color:
colorless or white.
Density:
2.1 - 2.2, Average = 2.15
Diaphaniety:
Transparent to Translucent
Habits:
Acicular - Occurs as needle-like crystals., Massive - Fibrous - Distinctly fibrous fine-grained forms., Radial - Crystals radiate from a center without producing stellar forms (e.g. s tibnite)
Hardness:
4-5 - Fluorite-Apatite
Luster:
Vitreous (Glassy)
Streak:
white
More details...