Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Disseminated - Occurs in small, distinct particles dispersed in matrix.
Massive - Granular - Common texture observed in granite and other igneous rock.
5.5 - Knife Blade
Vitreous - Greasy
Optical Properties of Allanite-(Y)
CI meas= 0.014 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.109 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1845,KPDmeas= 0.2042,KC= 0.207 Ncalc = 1.68 - 1.87
Biaxial (-), a=1.715-1.791, b=1.718-1.815, g=1.733-1.822, bire=0.0180-0.0310, 2V(Calc)=50-56, 2V(Meas)=40-80. Dispersion distinct to strong, r > v.
colorless, pale yellow, yellowish brown, pink, or greenish yellow.
yellowish brown, reddish brown, brownish green, dark reddish brown, or greenish brown.
pale yellow, brownish yellow, brownish green, green, or brown.
Calculated Properties of Allanite-(Y)
Bulk Density (Electron Density)=3.55 gm/cc note: Specific Gravity of Allanite-(Y) =3.75 gm/cc.
Fermion Index = 0.0082504498 Boson Index = 0.9917495502
PEAllanite-(Y) = 93.85 barns/electron U=PEAllanite-(Y) x relectron= 333.18 barns/cc.
GRapi = 14,180.81 (Gamma Ray American Petroleum Institute Units)
Concentration of Allanite-(Y) per GRapi unit = 70.52 (PPM)
Allanite-(Y) is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Radioactivity from Allanite-(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 / 7.99 cm
100 gm / 3.71 cm
10 gm / 1.72 cm
1 gm / 7.99 mm
0.1 gm / 3.71 mm
0.01 gm / 1.72 mm
0.001 gm / 0.80 mm
Weight of pure Allanite-(Y) in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.75 gm/cc.*
Goverment Estimate of Average Annual Exposure (
** 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 ( 0.70 % Th) From Sum REE Elements (14.04 % REE)
58.02.01c.03(58)Sorosilicate Insular, Mixed, Single, and Larger Tetrahedral Groups
(58.02)with cations in  and higher coordination; single and double groups (n=1,2)