S�o Jose do Sabug�, Para�ba, Brazil. Link to MinDat.org Location Data.
Name Origin:
Named for its composition and from the Greek for "shame," in allusion to the inability of chemists, at the time of its discovery, to separate some of its constituents.
Name Pronunciation:
Tantalaeschynite-(Y) + Pronunciation
Synonym:
Tantal-aeschynite-(Y) - Renamed Tantalaeschynite-(Y) by Mineralogical Record, v39 (2008), p131
Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habit:
Metamict - Mineral originally crystalline, now amorphous due to radiation damage.
Hardness:
5.5-6 - Knife Blade-Orthoclase
Luminescence:
Radioactive.
Luster:
Resinous
Streak:
yellowish brown
Optical Properties of Tantalaeschynite-(Y)
Optical Data:
Isotropic.
NCalc= 2.33 - from Gladstone-Dale relationship (KC = 0.1728) where Ncalc=Dcalc*KC+1 NCalc= 2.03 - from Gladstone-Dale relationship (KC = 0.1728) where Ncalc=Dmeas*KC+1
RL Color:
Dark gray with abundant white to dark red internal reflections.
Reflectivity
Standardized Intensity (100%) Reflection Spectra of Tantalaeschynite-(Y) in Air
λ
R
∑ R(λ)
470 nm
14.50
546 nm
14.20
589 nm
14.00
650 nm
14.00
Calculated Relative Intensity Colors of Tantalaeschynite-(Y) in Air
Relative Intensity
0%
70%
100%
140%
210%
280%
350%
420%
490%
560%
630%
R
Calculated Properties of Tantalaeschynite-(Y)
Electron Density:
Bulk Density (Electron Density)=6.61 gm/cc note: Specific Gravity of Tantalaeschynite-(Y) =7.68 gm/cc.
Fermion Index:
Fermion Index = 0.0038845967 Boson Index = 0.9961154033
Photoelectric:
PETantalaeschynite-(Y) = 716.11 barns/electron U=PETantalaeschynite-(Y) x relectron=4,734.34 barns/cc.
Radioactivity:
GRapi = 7,723.26 (Gamma Ray American Petroleum Institute Units)
Concentration of Tantalaeschynite-(Y) per GRapi unit = 129.48 (PPM)
Tantalaeschynite-(Y) is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Radioactivity from Tantalaeschynite-(Y) - 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 / 6.29 cm
188,409
5.09E-06
7,723.26
2.54
100 gm / 2.92 cm
18,841
5.09E-07
772.33
0.25
10 gm / 1.35 cm
1,884
5.09E-08
77.23
0.03
1 gm / 6.29 mm
188
5.09E-09
7.72
0.00
0.1 gm / 2.92 mm
19
5.09E-10
0.77
0.00
0.01 gm / 1.35 mm
2
5.09E-11
0.08
0.00
0.001 gm / 0.63 mm
0
5.09E-12
0.01
0.00
Weight of pure Tantalaeschynite-(Y) in grams (gm) and Calculated Diameter of a Sphere with a Density of 7.68 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 ( 0.42 % Th) From Sum REE Elements ( 8.41 % REE)
Tantalaeschynite-(Y) Classification
Dana Class:
08.03.06.04(08)Multiple Oxides with Nb, Ta, and Ti
Chemical Formula: 
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- mild