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Physical Properties of Prehnite
Cleavage:
{001} Distinct
Color:
Colorless, Gray, Yellow, Yellow green, White.
Density:
2.8 - 2.95, Average = 2.87
Diaphaneity:
Subtransparent to translucent
Fracture:
Brittle - Generally displayed by glasses and most non-metallic minerals.
Habit:
Globular - Spherical, or nearly so, rounded forms (e.g. wavellite).
Habit:
Reniform - "Kidney like" in shape (e.g.. hematite).
Habit:
Stalactitic - Shaped like pendant columns as stalactites or stalagmites (e.g. calcite).
Hardness:
6-6.5 - Orthoclase-Pyrite
Luminescence:
Fluorescent, Short UV=blue white mild peach, Long UV=yellow.
Luster:
Vitreous - Pearly
Streak:
colorless
Optical Properties of Prehnite
Gladstone-Dale:
CI meas= -0.025 (Excellent) - where the CI = (1-KPDmeas/KC) CI calc= -0.045 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2252,KPDmeas= 0.2209,KC= 0.2155 Ncalc = 1.6 - 1.64
Optical Data:
Biaxial (+), a=1.61-1.637, b=1.615-1.647, g=1.632-1.67, bire=0.0220-0.0330, 2V(Calc)=58-68, 2V(Meas)=64-70. Dispersion weak, r > v.
Pleochroism (x):
colorless.
Pleochroism (y):
colorless.
Calculated Properties of Prehnite
Electron Density:
Bulk Density (Electron Density)=2.86 gm/cc note: Specific Gravity of Prehnite =2.88 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEPrehnite = 3.70 barns/electron U=PEPrehnite x rElectron Density= 10.60 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Prehnite is Not Radioactive
Prehnite Classification
Dana Class:
72.01.03.01(72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
Chemical Formula: 
