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Physical Properties of Corundum
Cleavage:
None
Color:
Blue, Red, Yellow, Brown, Gray.
Density:
4 - 4.1, Average = 4.05
Diaphaneity:
Transparent to translucent
Fracture:
Tough - Difficult to break apart as shown by fibrous minerals and most metals.
Habit:
Euhedral Crystals - Occurs as well-formed crystals showing good external form.
Habit:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Habit:
Tabular - Form dimensions are thin in one direction.
Hardness:
9 - Corundum
Luminescence:
Sometimes Fluorescent, Long UV=red.
Luster:
Vitreous (Glassy)
Magnetism:
Nonmagnetic
Streak:
none
Optical Properties of Corundum
Gladstone-Dale:
CI meas= 0.089 (Poor) - where the CI = (1-KPDmeas/KC) CI calc= 0.08 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1905,KPDmeas= 0.1886,KC= 0.207 Ncalc = 1.83 - 1.85
Optical Data:
Uniaxial (-), e=1.76, w=1.768, bire=0.0080.
Calculated Properties of Corundum
Electron Density:
Bulk Density (Electron Density)=3.93 gm/cc note: Specific Gravity of Corundum =4.01 gm/cc.
Fermion Index:
Fermion Index = 0.0002259597 Boson Index = 0.9997740403
Photoelectric:
PECorundum = 1.54 barns/electron U=PECorundum x rElectron Density= 6.08 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Corundum is Not Radioactive
Chemical Formula: 
