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Physical Properties of Topaz
Cleavage:
{001} Perfect
Color:
Colorless, Pale blue, Yellow, Yellowish brown, Red.
Density:
3.5 - 3.6, Average = 3.55
Diaphaneity:
Transparent
Fracture:
Brittle - Uneven - Very brittle fracture producing uneven fragments.
Habit:
Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit:
Massive - Granular - Common texture observed in granite and other igneous rock.
Habit:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Hardness:
8 - Topaz
Luminescence:
Fluorescent, Short UV=golden yellow, Long UV=cream.
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Topaz
Gladstone-Dale:
CI meas= 0.146 (Poor) - where the CI = (1-KPDmeas/KC) CI calc= 0.193 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1653,KPDmeas= 0.1751,KC= 0.2049 Ncalc = 1.72 - 1.77
Optical Data:
Biaxial (+), a=1.606-1.629, b=1.609-1.631, g=1.616-1.638, bire=0.0090-0.0100, 2V(Calc)=58-68, 2V(Meas)=48-68. Dispersion noticeable, r > v.
Pleochroism (x):
colorless.
Pleochroism (y):
colorless.
Calculated Properties of Topaz
Electron Density:
Bulk Density (Electron Density)=3.51 gm/cc note: Specific Gravity of Topaz =3.55 gm/cc.
Fermion Index:
Fermion Index = 0.0074038512 Boson Index = 0.9925961488
Photoelectric:
PETopaz = 1.53 barns/electron U=PETopaz x rElectron Density= 5.36 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Topaz is Not Radioactive
Topaz Classification
Dana Class:
52.03.01.01(52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O
Chemical Formula: 
