General Information:
Chemical Formula:
Ca5(SiO4)2SO4
Composition:
(Molecular Weight = 480.62 gm)
Calcium 41.69 % Ca
Silicon 11.69 % Si
Sulfur 6.67 % S
Oxygen 39.95 % O
Empirical Formula:
Ca5(SiO4)2(SO4)
Environment:
In calcium-rich xenoliths in leucite tephrite lava.
IMA Status:
Approved IMA (Dana # Added)
Locality:
The Ettringer Bellerberg, near Mayen, Eifel, Germany.
Name Origin:
For Mr. B. Ternes of Mayen, Germany, who found the mineral and provided specimens for the study.
Physical Properties:
Cleavage:
None
Color:
colorless or bright blue.
Density:
2.94 - 2.98, Average = 2.96
Diaphaniety:
Transparent
Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Aggregates - Made of numerous individual crystals or clusters.,
Hardness:
4.5 - Between Fluorite and Apatite
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
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