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Physical Properties of Monazite-(Ce)
Cleavage:
{001} Distinct, {100} Indistinct
Color:
Brown, Colorless, Greenish, Gray white, Yellow.
Density:
4.8 - 5.5, Average = 5.15
Diaphaneity:
Subtransparent to subtranslucent
Fracture:
Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habit:
Crystalline - Fine - Occurs as well-formed fine sized crystals.
Habit:
Twinning Common - Crystals are usually twinned.
Hardness:
5-5.5 - Apatite-Knife Blade
Luminescence:
Non-fluorescent.
Luster:
Adamantine - Resinous
Streak:
grayish white
Optical Properties of Monazite-(Ce)
Gladstone-Dale:
CI meas= -0.003 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.032 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1517,KPDmeas= 0.1572,KC= 0.1567 Ncalc = 1.75 - 1.86
Optical Data:
Biaxial (+), a=1.785-1.8, b=1.787-1.801, g=1.837-1.849, bire=0.0490-0.0520, 2V(Calc)=18-24, 2V(Meas)=6-25. Dispersion r > v or r < v.
Pleochroism (x):
colorless or light yellow.
Pleochroism (y):
colorless or dark yellow.
Calculated Properties of Monazite-(Ce)
Electron Density:
Bulk Density (Electron Density)=4.58 gm/cc note: Specific Gravity of Monazite-(Ce) =5.15 gm/cc.
Fermion Index:
Fermion Index = 0.02 Boson Index = 0.98
Photoelectric:
PEMonazite-(Ce) = 407.22 barns/electron U=PEMonazite-(Ce) x relectron=1,864.04 barns/cc.
Radioactivity:
GRapi = 91,584.34 (Gamma Ray American Petroleum Institute Units)
Concentration of Monazite-(Ce) per GRapi unit = 10.92 (PPM)
Monazite-(Ce) is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Exposure (mRem**)/hr If Held in Hand For One Hour
1000 gm / 7.18 cm
2,163,839
5.85E-05
91,584.34
30.11
100 gm / 3.33 cm
216,384
5.85E-06
9,158.43
3.01
10 gm / 1.55 cm
21,638
5.85E-07
915.84
0.30
1 gm / 7.18 mm
2,164
5.85E-08
91.58
0.03
0.1 gm / 3.33 mm
216
5.85E-09
9.16
0.00
0.01 gm / 1.55 mm
22
5.85E-10
0.92
0.00
0.001 gm / 0.72 mm
2
5.85E-11
0.09
0.00
Weight of pure Monazite-(Ce) in grams (gm) and Calculated Diameter of a Sphere with a Density of 5.15 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
Chemical Formula: 
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