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 %
CaAluminum 3.90 %
AlIron 24.20 %
FeSilicon 16.22 %
SiHydrogen 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
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