General Information:
Chemical Formula:
Ca2(Fe+++,Al)3(SiO4)3(OH) = Ca2(Fe,Al)Al2(SiO4)(Si2O7)O(OH)
Composition:
(Molecular Weight = 519.30 gm)
Calcium 15.44 % Ca
Aluminum 3.90 % Al
Iron 24.20 % Fe
Silicon 16.22 % Si
Hydrogen 0.19 % H
Oxygen 40.05 % O
Empirical Formula:
Ca2Fe3+2.25Al0.75(SiO4)3(OH)
Environment:
Contact metamorphic rocks.
Locality:
Common world wide.
Name Origin:
From the Greek epidosis - "addition."
Physical Properties:
Cleavage:
[001] Perfect
Color:
yellowish green, brownish green, black, yellow, or gray.
Density:
3.3 - 3.6, Average = 3.45
Diaphaniety:
Transparent to translucent to opaque
Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Fibrous - Crystals made up of fibers., Massive - Uniformly indistinguishable crystals forming large masses.
Hardness:
7 - Quartz
Luminescence:
None.
Luster:
Vitreous (Glassy)
Streak:
grayish white
More details...