General Information:
Chemical Formula:
(K,Na)Ca2(Mg,Fe++,Al,Ti)5[(Si,Al)8O22](OH)2
Composition:
(Molecular Weight = 900.44 gm)
Potassium 3.26 % K
Sodium 0.64 % Na
Calcium 8.90 % Ca
Magnesium 6.75 % Mg
Titanium 1.33 % Ti
Aluminum 8.24 % Al
Iron 9.30 % Fe
Silicon 18.71 % Si
Hydrogen 0.22 % H
Oxygen 42.64 % O
Empirical Formula:
K0.75Na0.25Ca2Mg2.5Fe2+1.5Al0.75Ti0.25(Si6Al2O22)(OH)2
Environment:
Banded skarns and recrystallized limestones.
IMA Status:
Approved IMA
Locality:
Myojin Island, Ehime Prefecture, Japan.
Name Origin:
Named for the composition and for Ryoichi Sadanaga (1920-), professor emeritus, University of Tokyo.
Physical Properties:
Cleavage:
[110] Perfect
Color:
dark brown or black.
Density:
3.27
Diaphaniety:
Transparent to Translucent
Hardness:
6 - Orthoclase
Luster:
Vitreous (Glassy)
Streak:
light brown
More details...