General Information:
Chemical Formula:
NaCa2Si3O8(OH)
Composition:
(Molecular Weight = 332.40 gm)
Sodium 6.92 % Na
Calcium 24.11 % Ca
Silicon 25.35 % Si
Hydrogen 0.30 % H
Oxygen 43.32 % O
Empirical Formula:
NaCa2(Si3O8)(OH)
Environment:
Secondary mineral in basaltic rocks.
Locality:
Prospect Park quarry, northern New Jersey.
Name Origin:
From the Greek pektos - "compacted" and lithos - "stone."
Physical Properties:
Cleavage:
[001] Perfect, [100] Perfect
Color:
white, gray, light pink, or light green.
Density:
2.86
Diaphaniety:
Subtranslucent to translucent to opaque
Habits:
Acicular - Occurs as needle-like crystals., Globular - Spherical, or nearly so, rounded forms (e.g. wavellite)., Radial - Crystals radiate from a center without producing stellar form s (e.g. stibnite)
Hardness:
5 - Apatite
Luminescence:
None.
Luster:
Vitreous - Silky
Streak:
white
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