General Information:
Chemical Formula:
(Ce,Ca,Y)2(Al,Fe+++)3(SiO4)3(OH)
Composition:
(Molecular Weight = 614.71 gm)
Calcium 3.91 % Ca
Cerium 27.35 % Ce
Yttrium 4.34 % Y
Aluminum 9.88 % Al
Iron 6.81 % Fe
Silicon 13.71 % Si
Hydrogen 0.16 % H
Oxygen 33.84 % O
Empirical Formula:
Ce1.2Ca0.6Y0.3Al2.25Fe3+0.75(SiO4)3(OH)
IMA Status:
Approved IMA 1959
Locality:
TL: Greenland, Qaqarssuatsiaq
Name Origin:
Named after the Scottish mineralogist, T. Allan (1777-1833).
Physical Properties:
Cleavage:
[001] Imperfect, [100] Imperfect
Color:
brown, reddish brown, or black.
Density:
3.3 - 4.2, Average = 3.75
Diaphaniety:
Translucent to opaque
Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Disseminated - Occurs in small, distinct particles dispersed in matrix.,
Hardness:
5.5 - Knife Blade
Luminescence:
None.
Luster:
Vitreous - Greasy
Streak:
grayish brown
More details...