Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.
Habit:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Hardness:
7.5-8
Luster:
Metallic
Streak:
reddish brown
Optical Properties of Hibonite
Dichroism (e):
gray.
Dichroism (w):
brownish gray.
Optical Data:
Uniaxial (-).
NCalc= 1.85 - from Gladstone-Dale relationship (KC = 0.2109) where Ncalc=Dcalc*KC+1 NCalc= 1.81 - from Gladstone-Dale relationship (KC = 0.2109) where Ncalc=Dmeas*KC+1
Calculated Properties of Hibonite
Electron Density:
Bulk Density (Electron Density)=3.90 gm/cc note: Specific Gravity of Hibonite =4.01 gm/cc.
Fermion Index:
Fermion Index = 0.0059923554 Boson Index = 0.9940076446
Photoelectric:
PEHibonite = 22.00 barns/electron U=PEHibonite x relectron= 85.75 barns/cc.
Radioactivity:
GRapi = 4,081.56 (Gamma Ray American Petroleum Institute Units)
Concentration of Hibonite per GRapi unit = 245.00 (PPM)
Hibonite is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Radioactivity from Hibonite - mild
Specimen Size Weight/Volume (Sphere) *
Calculated Activity Bequerols (Bq)
Calculated Activity Curies (Ci)
Estimated Activity GR(api)
Estimated Exposure (mRem**)/hr If Held in Hand For One Hour
1000 gm / 7.81 cm
88,177
2.38E-06
4,081.56
1.34
100 gm / 3.62 cm
8,818
2.38E-07
408.16
0.13
10 gm / 1.68 cm
882
2.38E-08
40.82
0.01
1 gm / 7.81 mm
88
2.38E-09
4.08
0.00
0.1 gm / 3.62 mm
9
2.38E-10
0.41
0.00
0.01 gm / 1.68 mm
1
2.38E-11
0.04
0.00
0.001 gm / 0.78 mm
0
2.38E-12
0.00
0.00
Weight of pure Hibonite in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.01 gm/cc.*
Goverment Estimate of Average Annual Exposure (
360 mRem)
** Note: 10 microsieverts/hr = 1 mRem/hr **
Max Permissable Adult Dose 50,000 mRem/yr (hands), 15,000 mRem/yr (eyes)
Lethal Dose LD(50) Exposure 400,000 to 500,000 mRem
Estimated Thorium Activity ( 0.20 % Th) From Sum REE Elements ( 3.94 % REE)
Chemical Formula: 
- mild