General Information:
Chemical Formula:NaCa2Si3O8(OH)
Composition:(Molecular Weight = 332.40 gm)Sodium 6.92 %
NaCalcium 24.11 %
CaSilicon 25.35 %
SiHydrogen 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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