Biaxial (-), a=1.69, b=1.705, g=1.711, bire=0.0210, 2V(Calc)=64, 2V(Meas)=large. Dispersion r > v distinct.
Pleochroism (x):
anomalous blue.
Pleochroism (y):
anomalous blue.
Pleochroism (z):
anomalous blue.
Calculated Properties of Yftisite-(Y)
Electron Density:
Bulk Density (Electron Density)=4.09 gm/cc note: Specific Gravity of Yftisite-(Y) =4.47 gm/cc.
Fermion Index:
Fermion Index = 0.05 Boson Index = 0.95
Photoelectric:
PEYftisite-(Y) = 155.92 barns/electron U=PEYftisite-(Y) x relectron= 638.33 barns/cc.
Radioactivity:
GRapi = 10,663.23 (Gamma Ray American Petroleum Institute Units)
Concentration of Yftisite-(Y) per GRapi unit = 93.78 (PPM)
Yftisite-(Y) is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Radioactivity from Yftisite-(Y) - weak
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 / 7.53 cm
244,488
6.61E-06
10,663.23
3.51
100 gm / 3.50 cm
24,449
6.61E-07
1,066.32
0.35
10 gm / 1.62 cm
2,445
6.61E-08
106.63
0.04
1 gm / 7.53 mm
244
6.61E-09
10.66
0.00
0.1 gm / 3.50 mm
24
6.61E-10
1.07
0.00
0.01 gm / 1.62 mm
2
6.61E-11
0.11
0.00
0.001 gm / 0.75 mm
0
6.61E-12
0.01
0.00
Weight of pure Yftisite-(Y) in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.47 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 ( 0.55 % Th) From Sum REE Elements (10.91 % REE)
Yftisite-(Y) Classification
Dana Class:
52.04.04.03(52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O
(52.04)with cations in [6] and/or > [6] coordination
Chemical Formula: 
- weak