Secondary mineral associated with decomposed uraninite. Formed in a relatively dry environment in a restricted pH (6.5-11.5, non-acidic) range. Related to grimselite.
IMA Status:
Approved IMA 2003 (Dana # Added)
Locality:
Jachymov, NW Bohemia, Czech Republic. Link to MinDat.org Location Data.
Name Origin:
Named for Jiri Cejak (1929-) for his numerous contributions to the crystal chemistry of U minerals.
Microscopic Crystals - Crystals visible only with microscopes.
Habit:
Pseudo Hexagonal - Crystals show a hexagonal outline.
Luminescence:
Fluorescent, Short UV=weak yellow, Long UV=weak greenish yellow.
Luster:
Vitreous (Glassy)
Streak:
light yellow
Optical Properties of Cejkaite
Gladstone-Dale:
CI meas= -0.117 (Poor) - where the CI = (1-KPDmeas/KC) CI calc= -0.09 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1564,KPDmeas= 0.1602,KC= 0.1435 Ncalc = 1.53 - 1.54
Optical Data:
Biaxial (?), a=1.531, g=1.645, bire=0.1140
Calculated Properties of Cejkaite
Electron Density:
Bulk Density (Electron Density)=3.35 gm/cc note: Specific Gravity of Cejkaite =3.76 gm/cc.
Fermion Index:
Fermion Index = 0.0042818694 Boson Index = 0.9957181306
Photoelectric:
PECejkaite =1,143.16 barns/electron U=PECejkaite x relectron=3,829.64 barns/cc.
Radioactivity:
GRapi = 3,407,969.63 (Gamma Ray American Petroleum Institute Units)
Concentration of Cejkaite per GRapi unit = 293.43 (PPB)
Cejkaite is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Radioactivity from Cejkaite - very strong
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 / 7.98 cm
80,325,068
2.17E-03
3,407,969.63
1,120.43
100 gm / 3.70 cm
8,032,507
2.17E-04
340,796.96
112.04
10 gm / 1.72 cm
803,251
2.17E-05
34,079.70
11.20
1 gm / 7.98 mm
80,325
2.17E-06
3,407.97
1.12
0.1 gm / 3.70 mm
8,033
2.17E-07
340.80
0.11
0.01 gm / 1.72 mm
803
2.17E-08
34.08
0.01
0.001 gm / 0.80 mm
80
2.17E-09
3.41
0.00
Weight of pure Cejkaite in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.76 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