Keiviite-(Y) Mineral Data

General Keiviite-(Y) Information

Chemical Formula:

(Y,Yb)2Si2O7

Composition:

Molecular Weight = 388.05 gm

Yttrium 34.37 % Y 43.64 % Y₂O₃

Ytterbium 22.30 % Yb 25.39 % Yb₂O₃

Silicon 14.48 % Si 30.97 % SiO₂

Oxygen 28.86 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Y_1.5Yb_0.5Si₂O₇

Environment:

In fissures in quartz and fluorite in \amazonite" pegmatites.

IMA Status:

Approved IMA 1985

Locality:

Mt. Ploskaya, Keivy massif, Kola Peninsula, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for the relation to keiviite-(Yb) and the yttrium content.

Name Pronunciation:

Keiviite-(Y)

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Keiviite-(Y) Crystallography

Axial Ratios:

a:b:c =0.7639:1:0.5283

Cell Dimensions:

a = 6.845, b = 8.96, c = 4.734, Z = 2; beta = 101.65° V = 284.36 Den(Calc)= 4.53

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.23(1), 4.65(0.9), 3.04(0.8),

Physical Properties of Keiviite-(Y)

Cleavage:

{110} Perfect, {001} Indistinct

Color:

Colorless, White, Pink brown.

Density:

4.45

Diaphaneity:

Transparent

Hardness:

4-5 - Fluorite-Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Keiviite-(Y)

Gladstone-Dale:

CI meas= -0.012 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.006 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1633,KPDmeas= 0.1662,KC= 0.1642
Ncalc = 1.73 - 1.74

Optical Data:

Biaxial (-), a=1.713, b=1.748, g=1.758, bire=0.0450, 2V(Calc)=54, 2V(Meas)=55-56.

Calculated Properties of Keiviite-(Y)

Electron Density:

Bulk Density (Electron Density)=4.14 gm/cc
note: Specific Gravity of Keiviite-(Y) =4.53 gm/cc.

Fermion Index:

Fermion Index = 0.07
Boson Index = 0.93

Photoelectric:

PE_Keiviite-(Y)= 261.05 barns/electron
U=PE_Keiviite-(Y) x r_electron=1,081.85 barns/cc.

Radioactivity:

GRapi = 21,757.45 (Gamma Ray American Petroleum Institute Units)
Concentration of Keiviite-(Y) per GRapi unit = 45.96 (PPM)

Keiviite-(Y) is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.

**Estimated Radioactivity from Keiviite-(Y)** - weak
Specimen Size Weight/Volume (Sphere) *	Calculated Activity Becquerels (Bq)	Calculated Activity Curies (Ci)	Estimated Activity GR(api)	Estimated Exposure (mRem**)/hr If Held in Hand For One Hour
1000 gm / 7.50 cm	499,438	1.35E-05	21,757.45	7.15
100 gm / 3.48 cm	49,944	1.35E-06	2,175.74	0.72
10 gm / 1.62 cm	4,994	1.35E-07	217.57	0.07
1 gm / 7.50 mm	499	1.35E-08	21.76	0.01
0.1 gm / 3.48 mm	50	1.35E-09	2.18	0.00
0.01 gm / 1.62 mm	5	1.35E-10	0.22	0.00
0.001 gm / 0.75 mm	0	1.35E-11	0.02	0.00

Weight of pure Keiviite-(Y) in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.53 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 ( 1.11 % Th) From Sum REE Elements (22.30 % REE)

Keiviite-(Y) Classification

Dana Class:

55.02.01a.02 (55)Sorosilicate Si2O7 Groups, Generally with No Additional Anions

(55.02)with cations in [6] coordination

(55.02.01a)Thortveitite group

55.02.01a.01 Gittinsite CaZrSi2O7 C 2/m 2/m

55.02.01a.02 Keiviite-(Y) (Y,Yb)2Si2O7 C 2/m 2/m

55.02.01a.03 Keiviite-(Yb) (Yb,Y)2Si2O7 C 2/m 2/m

55.02.01a.04 Thortveitite (Sc,Y)2Si2O7 C 2/m 2/m

Strunz Class:

09.BC.05 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BC -Si2O7 groups, without non-tetrahedral anions;

09.BC.05 Keiviite-(Y) (Y,Yb)2Si2O7 C 2/m 2/m

09.BC.05 Gittinsite CaZrSi2O7 C 2/m 2/m

09.BC.05 Keiviite-(Yb) (Yb,Y)2Si2O7 C 2/m 2/m

09.BC.05 Thortveitite (Sc,Y)2Si2O7 C 2/m 2/m

09.BC.05 Yttrialite-(Y) (Y,Th)2Si2O7 P 2₁/m 2/m

Other Keiviite-(Y) Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Am.Min.,Vol.73,p191,1988) OPTIC PROP.(Am.Min.,Vol.73,p191,1988)

See Also:

Links to other databases for Keiviite-(Y) :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - Handbook of Mineralogy (UofA)
7 - MinDAT
8 - Mineralienatlas (Deutsch)
9 - Online Mineral Museum
10 - QUT Mineral Atlas
11 - Ruff.Info

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Print or Cut-and-Paste your Keiviite-(Y) Specimen Label here :

Keiviite-(Y)

(Y,Yb)2Si2O7
Dana No: 55.02.01a.02 Strunz No: 09.BC.05
Locality:

Notes: