General Information:
Chemical Formula:
NaK(Be,Al)Zr2(PO4)4·2(H2O)
Composition:
(Molecular Weight = 673.96 gm)
Potassium 5.80 % K
Sodium 3.41 % Na
Zirconium 27.07 % Zr
Beryllium 1.00 % Be
Aluminum 1.00 % Al
Phosphorus 18.38 % P
Hydrogen 0.60 % H
Oxygen 42.73 % O
Empirical Formula:
NaKBe0.75Al0.25Zr2(PO4)4·2(H2O)
Environment:
In pegmatitic cavities.
IMA Status:
Approved IMA
Locality:
A granite quarry near Wycheproof, NW Victoria, Australia.
Name Origin:
For A. R. C. Selwyn (1824-1902), founding director of the Geological Survey of Victoria, Australia.
Physical Properties:
Cleavage:
None
Color:
deep purplish blue.
Density:
2.94
Diaphaniety:
Transparent
Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), ,
Hardness:
4 - Fluorite
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
Streak:
pale lavender
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