Mineralogy Database

Kentbrooksite Mineral Data

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General Kentbrooksite Information

Help on Chemical  Formula: Chemical Formula: (Na,REE)15(Ca,REE)6Mn++Zr3NbSi25O74F2•2(H2O)
Help on Composition: Composition: Molecular Weight = 3,900.86 gm
   Sodium            5.30 %  Na    7.15 % Na2O
   Calcium           4.11 %  Ca    5.75 % CaO
   La,Ce,Pr,Nd,Sm,  29.53 %  RE   34.45 % REE2O3
   Zirconium         7.02 %  Zr    9.48 % ZrO2
   Manganese         1.41 %  Mn    1.82 % MnO
   Niobium           2.38 %  Nb    3.41 % Nb2O5
   Silicon          18.00 %  Si   38.51 % SiO2
   Hydrogen          0.10 %  H     0.92 % H2O
   Oxygen           31.17 %  O
   Fluorine          0.97 %  F     0.97 % F
                      -   %   F    -0.41 % -O=F2    
                   ______        ______ 
                   100.00 %      102.05 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Na9REE6Ca4REE2Mn2+Zr3NbSi25O74F2•2(H2O)
Help on Environment: Environment: A manganese and fluorine rich member of the eudialyte group in alkaline pegmatite bodies cutting pulaskite rocks.
Help on IMA Status: IMA Status: Approved IMA 1998 (Dana # Added)
Help on Locality: Locality: Amdrup Fjord, Kangerdlugssuaq intrustion, East Greenland. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: For Dr. C. Kent Brooks (1943-), leader of fourteen geological expeditions to the Kangerdlugssuaq area of east Greenland.
Help on Name Pronunciation: Name Pronunciation: Kentbrooksite + Pronunciation Say KENTBROOKSITE
Help on Synonym: Synonym: IMA1996-023

Kentbrooksite Image

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Comments: Orange translucent crystals of kentbrooksite frozen in syenite rock.
Location: Mount Alluiav, Lovozero Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Kentbrooksite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:2.12342
Help on Cell Dimensions: Cell Dimensions: a = 14.168, c = 30.0847, Z = 3; V = 5,229.90 Den(Calc)= 3.72
Help on Crystal System: Crystal System: Trigonal - Ditrigonal Pyramidal H-M Symbol (3m) Space Group: R 3m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.839(1), 2.961(0.91), 11.385(0.43),

Physical Properties of Kentbrooksite

Help on Cleavage: Cleavage: None
Help on Color: Color: Yellowish brown.
Help on Density: Density: 3.07 - 3.1, Average = 3.08
Help on Diaphaneity: Diaphaneity: Transparent
Help on Fracture: Fracture: Brittle - Uneven - Very brittle fracture producing uneven fragments.
Help on Habit: Habit: Aggregates - Made of numerous individual crystals or clusters.
Help on Habit: Habit: Anhedral Grains - Granular minerals without the expression of crystal shapes
Help on Hardness: Hardness: 5-6 - Between Apatite and Orthoclase
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Kentbrooksite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.084 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.101 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1681,KPDmeas= 0.2028,KC= 0.187
Ncalc = 1.57 - 1.7
Help on Optical Data: Optical Data: Uniaxial (-), e=1.623, w=1.628, bire=0.0050.

Calculated Properties of Kentbrooksite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.90 gm/cc
note: Specific Gravity of Kentbrooksite =3.09 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.07
Boson Index = 0.93
Help on Photoelectric: Photoelectric: PEKentbrooksite = 192.91 barns/electron
U=PEKentbrooksite x relectron= 559.29 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 29,710.50 (Gamma Ray American Petroleum Institute Units)
Concentration of Kentbrooksite per GRapi unit = 33.66 (PPM)

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

Estimated Radioactivity from Kentbrooksite - weak
Curies (Ci)
If Held in Hand
For One Hour
1000 gm / 8.52 cm 663,891 1.79E-05 29,710.50 9.77
100 gm / 3.96 cm 66,389 1.79E-06 2,971.05 0.98
10 gm / 1.84 cm 6,639 1.79E-07 297.10 0.10
1 gm / 8.52 mm 664 1.79E-08 29.71 0.01
0.1 gm / 3.96 mm 66 1.79E-09 2.97 0.00
0.01 gm / 1.84 mm 7 1.79E-10 0.30 0.00
0.001 gm / 0.85 mm 1 1.79E-11 0.03 0.00

Weight of pure Kentbrooksite in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.09 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 ( 1.48 % Th) From Sum REE Elements (29.53 % REE)

Kentbrooksite Classification

Help on  Dana Class: Dana Class: (64)Cyclosilicates
  (64.01)Cyclosilicate Rings with Other Anions and Insular Silicate Groups with mixed ring types
  (64.01.01)Eudialyte Group Eudialyte Na4(Ca,Ce)2(Fe,Mn,Y)ZrSi8O22(OH,Cl)2(?) R 3m 3 2/m Alluaivite Na19(Ca,Mn)6(Ti,Nb)3(Si3O9)2(Si10O28)2Cl•2(H2O) R 3m 3 2/m Kentbrooksite! (Na,REE)15(Ca,REE)6MnZr3NbSi25O74F2•2(H2O) R 3m 3m Khomyakovite! Na12Sr3Ca6Fe3Zr3W(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3m 3m Manganokhomyakovite! Na12Sr3Ca6Mn3Zr3W(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3m 3m Oneillite! Na15Ca3Mn3Fe3Zr3Nb(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3 3 Ferrokentbrooksite! Na15Ca6(Fe,Mn)3Zr3NbSi25O73(O,OH,H2O)3(Cl,F,OH)2 R 3m 3m Ikranite! (Na,H3O)15(Ca,Mn,REE)6Fe2Zr3([],Zr)([],Si)Si24O66(O,OH)6Cl•2-3H2O R 3m 3m Feklichevite! Na11Ca9(Fe,Fe)2Zr3Nb[Si25O73](OH,H2O,Cl,O)5 R 3m 3m Rastsvetaevite! Na27K8Ca12Fe3Zr6Si52O144(O,OH,H2O)6Cl2 R 3m 3m Taseqite! Na12Sr3Ca6Fe3Zr3NbSi25O73(O,OH,H2O)3Cl2 R 3m 3m Carbokentbrooksite! (Na,[])12(Na,Ce)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)•H2O R 3m 3m Zirsilite-(Ce)! (Na,[])12(Ce,Na)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)•H2O R 3m 3m Labyrinthite! (Na,K,Sr)35Ca12Fe3Zr6TiSi51O144(O,OH,H2O)9Cl3 R 3m 3m Aqualite! (H3O)8(Na,K,Sr)5Ca6Zr3Si26O66(OH)9Cl R 3m 3m Raslakite! Na15Ca3Fe3(Na,Zr)3Zr3(Si,Nb)(Si25O73)(OH,H2O)3(Cl,OH) R 3m 3m Georgbarsanovite! Na12(Mn,Sr,REE)3Ca6Fe3Zr3NbSi25O76Cl2•H2O R 3m 3m Johnsenite-(Ce)! Na12(Ce,REE,Sr)3Ca6Mn3Zr3W(Si25O73)(CO3)(OH,Cl)2 R 3m 3m Golyshevite! (Na,Ca)10Ca9(Fe,Fe)2Zr3NbSi25O72(CO3)(OH)3•H2O R 3m 3m Mogovidite! Na9(Ca,Na)6Ca6Fe2Zr3[]Si25O72(CO3)(OH)4 R 3m 3m Dualite! Na30(Ca,Na,Ce,Sr)12(Na,Mn,Fe,Ti)6Zr3Ti3MnSi51O144(OH,H2O,Cl)9 R 3m 3m Voronkovite! Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl•H2O R 3 3
Help on  Strunz Class: Strunz Class: 09.CO.10 09 - SILICATES (Germanates)
  09.C - Cyclosilicates
  09.CO -[Si9O27]18- 9-membered rings
09.CO.10 Alluaivite Na19(Ca,Mn)6(Ti,Nb)3(Si3O9)2(Si10O28)2Cl•2(H2O) R 3m 3 2/m
09.CO.10 Eudialyte Na4(Ca,Ce)2(Fe,Mn,Y)ZrSi8O22(OH,Cl)2(?) R 3m 3 2/m
09.CO.10 Kentbrooksite! (Na,REE)15(Ca,REE)6MnZr3NbSi25O74F2•2(H2O) R 3m 3m
09.CO.10 Labyrinthite! (Na,K,Sr)35Ca12Fe3Zr6TiSi51O144(O,OH,H2O)9Cl3 R 3m 3m
09.CO.10 Carbokentbrooksite! (Na,[])12(Na,Ce)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)•H2O R 3m 3m
09.CO.10 Zirsilite-(Ce)! (Na,[])12(Ce,Na)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)•H2O R 3m 3m
09.CO.10 Mogovidite! Na9(Ca,Na)6Ca6Fe2Zr3[]Si25O72(CO3)(OH)4 R 3m 3m
09.CO.10 Voronkovite! Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl•H2O R 3 3
09.CO.10 Taseqite! Na12Sr3Ca6Fe3Zr3NbSi25O73(O,OH,H2O)3Cl2 R 3m 3m
09.CO.10 Aqualite! (H3O)8(Na,K,Sr)5Ca6Zr3Si26O66(OH)9Cl R 3m 3m
09.CO.10 Raslakite! Na15Ca3Fe3(Na,Zr)3Zr3(Si,Nb)(Si25O73)(OH,H2O)3(Cl,OH) R 3m 3m
09.CO.10 Feklichevite! Na11Ca9(Fe,Fe)2Zr3Nb[Si25O73](OH,H2O,Cl,O)5 R 3m 3m
09.CO.10 Ikranite! (Na,H3O)15(Ca,Mn,REE)6Fe2Zr3([],Zr)([],Si)Si24O66(O,OH)6Cl•2-3H2O R 3m 3m
09.CO.10 Khomyakovite! Na12Sr3Ca6Fe3Zr3W(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3m 3m
09.CO.10 Manganokhomyakovite! Na12Sr3Ca6Mn3Zr3W(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3m 3m
09.CO.10 Oneillite! Na15Ca3Mn3Fe3Zr3Nb(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3 3
09.CO.10 Ferrokentbrooksite! Na15Ca6(Fe,Mn)3Zr3NbSi25O73(O,OH,H2O)3(Cl,F,OH)2 R 3m 3m
09.CO.10 Rastsvetaevite! Na27K8Ca12Fe3Zr6Si52O144(O,OH,H2O)6Cl2 R 3m 3m
09.CO.10 Johnsenite-(Ce)! Na12(Ce,REE,Sr)3Ca6Mn3Zr3W(Si25O73)(CO3)(OH,Cl)2 R 3m 3m
09.CO.10 Georgbarsanovite! Na12(Mn,Sr,REE)3Ca6Fe3Zr3NbSi25O76Cl2•H2O R 3m 3m
09.CO.10 Golyshevite! (Na,Ca)10Ca9(Fe,Fe)2Zr3NbSi25O72(CO3)(OH)3•H2O R 3m 3m
09.CO.10 Dualite! Na30(Ca,Na,Ce,Sr)12(Na,Mn,Fe,Ti)6Zr3Ti3MnSi51O144(OH,H2O,Cl)9 R 3m 3m

Other Kentbrooksite Information

Help on References: References: NAME( MinRec) PHYS. PROP.(Eur. J. Min.,Vol.10,p207-219,1998) OPTIC PROP.(MinRec)
Help on See Also: See Also: Links to other databases for Kentbrooksite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - MinDAT
9 - Mineralienatlas (Deutsch)
10 - Online Mineral Museum
11 - QUT Mineral Atlas
12 - Ruff.Info

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Dana No: Strunz No: 09.CO.10





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