Semenovite Mineral Data

Semenovite Mineral Data +

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General Semenovite Information

Chemical Formula:

(Na,Ca)9(Ce,La)2(Fe++,Mn)(Si,Be)20(O,OH,F)48

Composition:

Molecular Weight = 1,853.28 gm

Potassium 0.21 % K 0.25 % K₂O

Sodium 8.31 % Na 11.20 % Na₂O

Calcium 4.33 % Ca 6.05 % CaO

Lanthanum 6.00 % La 7.03 % La₂O₃

Cerium 5.29 % Ce 6.20 % Ce₂O₃

La,Ce,Pr,Nd,Sm, 3.11 % RE 3.63 % REE₂O₃

Yttrium 1.44 % Y 1.83 % Y₂O₃

Manganese 1.48 % Mn 1.91 % MnO

Beryllium 3.01 % Be 8.37 % BeO

Aluminum 0.44 % Al 0.83 % Al₂O₃

Zinc 0.35 % Zn 0.44 % ZnO

Iron 2.41 % Fe 0.78 % FeO / 2.59 % Fe₂O₃

Silicon 20.46 % Si 43.77 % SiO₂

Hydrogen 0.22 % H 1.94 % H₂O

Oxygen 38.33 % O

Fluorine 4.61 % F 4.61 % F

- % F -1.94 % -O=F₂

______ ______

100.00 % 99.48 % = TOTAL OXIDE

Empirical Formula:

Na_6.7Ca₂K_0.1La_0.8Ce_0.7Y_0.3REE_0.4Mn²⁺_0.5Fe²⁺_0.2Zn_0.1Fe³⁺_0.6Si_13.5Be_6.2 Al_0.3O_40.4F_4.5(OH)₄

Environment:

Occurs in border zone of the only epididymite-eudidymite bearing albitite, in cavities and fractures.

IMA Status:

Approved IMA 1972

Locality:

Ilimaussaq complex, South Greenland. Link to MinDat.org Location Data.

Name Origin:

Named for Yevgeny Ivanovich Semenov, (1951-), Russian mineralogist, IMGRE, Moscow, Russia.

Semenovite Image

Images:

Semenovite

Comments: Tan crystals of semenovite to 1 mm across on matrix.
Location: Ilimaussaq, Tasseq, Greenland. Scale: Picture size 1 cm.
© John Veevaert

Semenovite Crystallography

Axial Ratios:

a:b:c =1.0031:1:0.7186

Cell Dimensions:

a = 13.879, b = 13.835, c = 9.942, Z = 2; V = 1,909.02 Den(Calc)= 3.22

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pmmn

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

By Intensity(I/I_o): 2.73(1), 2.84(1), 3.28(1),

Crystal Structure:

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Mazzi F , Ungaretti L , Dal Negro A , Petersen O V , Ronsbo J G , American Mineralogist , 64 (1979) p.202-210, The crystal structure of semenovite

Physical Properties of Semenovite

Cleavage:

None

Color:

Brown, Orange brown, Gray, Reddish brown, Colorless.

Density:

3.14

Diaphaniety:

Transparent to translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Pseudo Tetragonal - Crystals show a tetragonal shape.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

3.5-4 - Copper Penny-Fluorite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Semenovite

Gladstone-Dale:

CI meas= 0.012 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.037 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1887,KPDmeas= 0.1935,KC= 0.1959

Optical Data:

Biaxial (-), a=1.595, b=1.614, g=1.614, bire=0.0190, 2V(Calc)=0, 2V(Meas)=0-55.

Calculated Properties of Semenovite

Electron Density:

r_electron=3.02 gm/cc
note: r_Semenovite=3.14 gm/cc.

Fermion Index

Fermion Index = 0.04643
Boson Index = 0.95357

Photoelectric:

PE_Semenovite= 75.11 barns/electron
U=PE_Semenovite x r_electron= 226.92 barns/cc.

Radioactivity:

GRapi = 14,789.78 (Gamma Ray American Petroleum Institute Units)

Semenovite is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.

**Estimated Radioactivity from Semenovite** - 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 / 8.47 cm	322,792	8.72E-06	14,789.78	4.86
100 gm / 3.93 cm	32,279	8.72E-07	1,478.98	0.49
10 gm / 1.83 cm	3,228	8.72E-08	147.90	0.05
1 gm / 8.47 mm	323	8.72E-09	14.79	0.00
0.1 gm / 3.93 mm	32	8.72E-10	1.48	0.00
0.01 gm / 1.83 mm	3	8.72E-11	0.15	0.00
0.001 gm / 0.85 mm	0	8.72E-12	0.01	0.00

Weight of pure Semenovite in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.14 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 ( 0.72 % Th) From Sum REE Elements (14.40 % REE)

Semenovite Classification

Dana Class:

72.5.2.4 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.5)with corrugated and complex layers

(72.5.2)Leucospenite and related species

72.5.2.1 Leucosphenite Na4BaTi2O2[B2Si10O28] C 2/m 2/m

72.5.2.2 Nordite-(Ce) (Ce,La,Ca)(Sr,Ca)Na2(Na,Mn)(Zn,Mg)Si6O17 Pcca 2/m 2/m 2/m

72.5.2.3 Nordite-(La) (Na,Mn)3(Sr,Ca)(La,Ce)(Zn,Mg)Si6O17 Pcca 2/m 2/m 2/m

72.5.2.4 Semenovite (Na,Ca)9(Ce,La)2(Fe,Mn)(Si,Be)20(O,OH,F)48 Pmmn 2/m 2/m 2/m

72.5.2.5 Ferronordite-(Ce)! Na3SrCeFeSi6O17 Pcca 2/m 2/m 2/m

72.5.2.6 Manganonordite-(Ce)! Na3SrCeMnSi6O17 Pcca 2/m 2/m 2/m

72.5.2.7 Ferronordite-(La)! Na3Sr(La,Ce)FeSi6O17 Pcca 2/m 2/m 2/m

Strunz Class:

VIII/G.03-10 VIII - Silicates

VIII/G - Intermediate between chain- and layered silicates

VIII/G.03 - Semenovite-(Ce) - Nordite-(La) series

VIII/G.03-10 Semenovite (Na,Ca)9(Ce,La)2(Fe,Mn)(Si,Be)20(O,OH,F)48 Pmmn 2/m 2/m 2/m

VIII/G.03-20 Nordite-(Ce) (Ce,La,Ca)(Sr,Ca)Na2(Na,Mn)(Zn,Mg)Si6O17 Pcca 2/m 2/m 2/m

VIII/G.03-30 Nordite-(La) (Na,Mn)3(Sr,Ca)(La,Ce)(Zn,Mg)Si6O17 Pcca 2/m 2/m 2/m

VIII/G.03-40 Ferronordite-(Ce)! Na3SrCeFeSi6O17 Pcca 2/m 2/m 2/m

VIII/G.03-45 Ferronordite-(La)! Na3Sr(La,Ce)FeSi6O17 Pcca 2/m 2/m 2/m

VIII/G.03-50 Manganonordite-(Ce)! Na3SrCeMnSi6O17 Pcca 2/m 2/m 2/m

Other Semenovite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Semenovite :
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
10 - Ruff.Info
11 - WWW-MINCRYST

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Print or Cut-and-Paste your Semenovite Specimen Label here :

Semenovite

(Na,Ca)9(Ce,La)2(Fe++,Mn)(Si,Be)20(O,OH,F)48
Dana No: 72.5.2.4 Strunz No: VIII/G.03-10
Locality:

Notes: