Polyakovite-(Ce) Mineral Data

Polyakovite-(Ce) Mineral Data

General Polyakovite-(Ce) Information

Chemical Formula:

(Ce,La,Nd,Pr,Ca)4(Mg,Fe++)(Cr,Fe+++)2(Ti,Nb)2Si4O22

Composition:

Molecular Weight = 1,255.42 gm

Calcium 0.64 % Ca 0.89 % CaO

Lanthanum 13.28 % La 15.57 % La₂O₃

Cerium 21.21 % Ce 24.84 % Ce₂O₃

Praeseodymium 2.24 % Pr 2.63 % Pr₂O₃

Thorium 1.85 % Th 2.10 % ThO₂

Magnesium 1.55 % Mg 2.57 % MgO

Titanium 5.72 % Ti 9.54 % TiO₂

Niobium 2.96 % Nb 4.23 % Nb₂O₅

Chromium 4.97 % Cr 7.26 % Cr₂O₃

Iron 4.00 % Fe 1.14 % FeO / 4.45 % Fe₂O₃

Silicon 8.95 % Si 19.14 % SiO₂

Neodymium 4.60 % Nd 5.36 % Nd₂O₃

Oxygen 28.04 % O

______ ______

100.00 % 99.75 % = TOTAL OXIDE

Empirical Formula:

Ce_1.9La_1.2Nd_0.4Pr_0.2Ca_0.2Th_0.1Mg_0.8Fe²⁺_0.2Cr_1.2Fe³⁺_0.7Ti_1.5Nb_0.4Si₄O₂₂

Environment:

In a carbonatite vein and in phlogopite-fluororichterite rocks. Cr analogue of chevkinite-(Ce), structure

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

N97 mine, Ilmen Natural Reserve, southern Urals, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for Vladislav O. Polyakoy (1950-1993), Russian mineralogist.

Synonym:

IMA1998-029

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Polyakovite-(Ce) Crystallography

Axial Ratios:

a:b:c =2.3515:1:1.938

Cell Dimensions:

a = 13.397, b = 5.697, c = 11.041, Z = 2; beta = 100.53° V = 828.49 Den(Calc)= 5.03

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): 2.715(1)(004), 3.18(0.5)(311), 2.16(0.45)(421),2.849(0.4)(020), 3.15(0.4)(312), 5.44(0.4)(002), 3.12(0.35), 3.62(0.35),

Crystal Structure:

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Popov V A , Pautov L A , Sokolova E V , Hawthorne F C , McCammon C A , Bazhenova L F , The Canadian Mineralogist , 39 (2001) p.1095-1104, Polyakovite-(Ce), (REE,Ca)4(Mg,Fe)(Cr,Fe)2(Ti,Nb)2Si4O22, a new metamict, mineral species from the Ilmen Mountains, Southern Urals, Russia: Mineral, discription and crystal chemistry, Locality: Ilmen Mountains, Southern Urals, Russia

Physical Properties of Polyakovite-(Ce)

Color:

Black.

Density:

4.75

Diaphaniety:

Opaque to translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Amorphous - No crystalline form or imitative shape.

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Metamict - Mineral originally crystalline, now amorphous due to radiation damage.

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luster:

Resinous

Streak:

light brown

Optical Properties of Polyakovite-(Ce)

Gladstone-Dale:

CI meas= 0.038 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.091 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1855,KPDmeas= 0.1964,KC= 0.2042

Optical Data:

Isotropic, n=1.931-1.935.

RL Color:

Gray.

RL Pleochroism:

None.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Polyakovite-(Ce) in Air**
λ	R	∑ R(λ)
480 nm	11.10
540 nm	10.90
580 nm	10.80
640 nm	10.50

**Calculated Relative Intensity Colors of Polyakovite-(Ce) in Air**
Relative Intensity	0%	90%	100%	180%	270%	360%	450%	540%	630%	720%	810%	820%
R

Calculated Properties of Polyakovite-(Ce)

Electron Density:

r_electron=4.32 gm/cc
note: r_{Polyakovite-(Ce)}=4.75 gm/cc.

Fermion Index

Fermion Index = 0.02837
Boson Index = 0.97163

Photoelectric:

PE_{Polyakovite-(Ce)}= 260.59 barns/electron
U=PE_{Polyakovite-(Ce)} x r_electron=1,125.20 barns/cc.

Radioactivity:

GRapi = 35,842.90 (Gamma Ray American Petroleum Institute Units)

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

Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 10 cm box) 848.61 ±212.15 grams of pure Polyakovite-(Ce) .

**Estimated Radioactivity from Polyakovite-(Ce)** - 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 / 7.38 cm	828,034	2.24E-05	35,842.90	11.78
100 gm / 3.43 cm	82,803	2.24E-06	3,584.29	1.18
10 gm / 1.59 cm	8,280	2.24E-07	358.43	0.12
1 gm / 7.38 mm	828	2.24E-08	35.84	0.01
0.1 gm / 3.43 mm	83	2.24E-09	3.58	0.00
0.01 gm / 1.59 mm	8	2.24E-10	0.36	0.00
0.001 gm / 0.74 mm	1	2.24E-11	0.04	0.00

Weight of pure Polyakovite-(Ce) in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.75 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

Polyakovite-(Ce) Classification

Dana Class:

56.2.8.7 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.2)with cations in [4] and/or >[4] coordination

(56.2.8)Perierite - Chevkinite group

56.2.8.1 Chevkinite-(Ce) (Ce,La,Ca,Th)4(Fe,Mg)2(Ti,Fe)3Si4O22 C 2/m 2/m

56.2.8.2 Strontiochevkinite (Sr,REE)4Fe(Ti,Zr)2Ti2Si4O22 C 2/a 2/m

56.2.8.3 Perrierite-(Ce) (Ce,La,Ca)4(Fe,Mg)2(Ti,Fe)3Si4O22 C 21/a 2/m

56.2.8.4 Orthochevkinite* (Ce,La,Ca,Na,Th)4(Fe,Mg)2(Ti,Fe)3Si4O22 Unk Ortho

56.2.8.5 Rengeite! Sr4ZrTi4Si4O22 P 2₁/a 2/m

56.2.8.6 Matsubaraite! Sr4TiTi4Si4O22 P 2₁/a 2/m

56.2.8.7 Polyakovite-(Ce) ! (Ce,La,Nd,Pr,Ca)4(Mg,Fe)(Cr,Fe)2(Ti,Nb)2Si4O22 C 2/m 2/m

56.2.8.8 IMA2003-017! (REE,Ca)4(Fe,Ti,Fe,[])(Ti,Fe,Fe,Nb)4Si4O22 C 2/m 2/m

Strunz Class:

VIII/C.17-25 VIII - Silicates

VIII/C - Sorosilicates with [Si2O7]6-, with anions unfamiliar to tetraheders [O,OH,F]

VIII/C.17 - Fresnoite - Belkovite series

VIII/C.17-05 Matsubaraite! Sr4TiTi4Si4O22 P 2₁/a 2/m

VIII/C.17-15 Rengeite! Sr4ZrTi4Si4O22 P 2₁/a 2/m

VIII/C.17-25 Polyakovite-(Ce) (Ce,La,Nd,Pr,Ca)4(Mg,Fe)(Cr,Fe)2(Ti,Nb)2Si4O22 C 2/m 2/m

VIII/C.17-30 Perrierite-(Ce) (Ce,La,Ca)4(Fe,Mg)2(Ti,Fe)3Si4O22 C 21/a 2/m

Other Polyakovite-(Ce) Information

References:

NAME( AmMin, Vol 87, p 766) PHYS. PROP.(AmMin, Vol 87, p 766) OPTIC PROP.(AmMin, Vol 87, p 766)

See Also:

Links to other databases for Polyakovite-(Ce) :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas

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Polyakovite-(Ce)

(Ce,La,Nd,Pr,Ca)4(Mg,Fe++)(Cr,Fe+++)2(Ti,Nb)2Si4O22
Dana No: 56.2.8.7 Strunz No: VIII/C.17-25
Locality:

Notes: