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Physical Properties of Johannite
Cleavage:
{100} Good
Color:
Yellow, Greenish yellow.
Density:
3.3 - 3.5, Average = 3.4
Diaphaneity:
Transparent to Translucent
Fracture:
Irregular - Flat surfaces (not cleavage) fractured in an irregular pattern.
Habit:
Druse - Crystal growth in a cavity which results in numerous crystal tipped surfaces.
Habit:
Massive - Uniformly indistinguishable crystals forming large masses.
Habit:
Reniform - "Kidney like" in shape (e.g.. hematite).
Hardness:
2 - Gypsum
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
Streak:
light green
Optical Properties of Johannite
Gladstone-Dale:
CI meas= -0.104 (Poor) - where the CI = (1-KPDmeas/KC) CI calc= -0.107 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1753,KPDmeas= 0.1748,KC= 0.1584 Ncalc = 1.52 - 1.55
Estimated Radioactivity from Johannite - 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 / 8.25 cm
87,501,143
2.36E-03
3,756,556.78
1,235.03
100 gm / 3.83 cm
8,750,114
2.36E-04
375,655.68
123.50
10 gm / 1.78 cm
875,011
2.36E-05
37,565.57
12.35
1 gm / 8.25 mm
87,501
2.36E-06
3,756.56
1.24
0.1 gm / 3.83 mm
8,750
2.36E-07
375.66
0.12
0.01 gm / 1.78 mm
875
2.36E-08
37.57
0.01
0.001 gm / 0.83 mm
88
2.36E-09
3.76
0.00
Weight of pure Johannite in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.40 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
Johannite Classification
Dana Class:
31.08.02.01(31)Hydrated Sulfates Containing Hydroxyl or Halogen