General Information:
Chemical Formula:
(K,Na)3(Fe++,Mn)7Ti2Si8O24(O,OH)7
Composition:
(Molecular Weight = 1,312.74 gm)
Potassium 6.70 % K
Sodium 1.31 % Na
Titanium 7.29 % Ti
Manganese 7.32 % Mn
Iron 22.33 % Fe
Silicon 17.12 % Si
Hydrogen 0.13 % H
Oxygen 37.78 % O
Empirical Formula:
K2.25Na0.75Fe2+5.25Mn2+1.75Ti2Si8O29.25OH1.75
Environment:
Mineral in zircon-bearing syenites.
Locality:
Langesundfiord, near Brevik, Norway.
Name Origin:
From the Greek aster - "star" and fyllon - "leaf."
Physical Properties:
Cleavage:
[001] Perfect
Color:
brown, brownish red, bronze yellow, or gold yellow.
Density:
3.3 - 3.4, Average = 3.34
Diaphaniety:
Translucent to Opaque
Habits:
Bladed - Aggregates of thin lath-like crystals (e.g. kyanite)., Stellate - Occurs as spherical, radial aggregates radiating from a "star" like point., Crystalline - Fine - Occurs as w ell-formed fine sized crystals.
Hardness:
3-3.5 - Calcite-Copper Penny
Luminescence:
None.
Luster:
Adamantine - Pearly
Streak:
yellowish brown
More details...