Kentbrooksite Mineral Data

General Kentbrooksite Information

Chemical Formula:

(Na,REE)15(Ca,REE)6Mn++Zr3NbSi25O74F2•2(H2O)

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

Empirical Formula:

Na₉REE₆Ca₄REE₂Mn²⁺Zr₃NbSi₂₅O₇₄F₂•2(H₂O)

Environment:

A manganese and fluorine rich member of the eudialyte group in alkaline pegmatite bodies cutting pulaskite rocks.

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

Amdrup Fjord, Kangerdlugssuaq intrustion, East Greenland. Link to MinDat.org Location Data.

Name Origin:

For Dr. C. Kent Brooks (1943-), leader of fourteen geological expeditions to the Kangerdlugssuaq area of east Greenland.

Name Pronunciation:

Kentbrooksite + Pronunciation

Synonym:

IMA1996-023

Kentbrooksite Image

Images:

Kentbrooksite

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

Axial Ratios:

a:c = 1:2.12342

Cell Dimensions:

a = 14.168, c = 30.0847, Z = 3; V = 5,229.90 Den(Calc)= 3.72

Crystal System:

Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: R 3m

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

By Intensity(I/I_o): 2.839(1), 2.961(0.91), 11.385(0.43),

Crystal Structure:

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Johnsen O , Grice J D , Gault R A , European Journal of Mineralogy , 10 (1998) p.207-219, Kentbrooksite from the Kangerdlugssuaq intrusion, East Greenland,, a new Mn-REE-Nb-F end-member in a series within the eudialyte group:, Description and crystal structure, Locality: Kangerdlugssuaq intrusion, East Greenland

Physical Properties of Kentbrooksite

Cleavage:

None

Color:

Yellowish brown.

Density:

3.07 - 3.1, Average = 3.08

Diaphaneity:

Transparent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Anhedral Grains - Granular minerals without the expression of crystal shapes

Hardness:

5-6 - Between Apatite and Orthoclase

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Kentbrooksite

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

Optical Data:

Uniaxial (-), e=1.623, w=1.628, bire=0.0050.

Calculated Properties of Kentbrooksite

Electron Density:

Bulk Density (Electron Density)=2.90 gm/cc
note: Specific Gravity of Kentbrooksite =3.09 gm/cc.

Fermion Index:

Fermion Index = 0.07
Boson Index = 0.93

Photoelectric:

PE_{Kentbrooksite}= 192.91 barns/electron
U=PE_{Kentbrooksite} x r_electron= 559.29 barns/cc.

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
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 / 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

Dana Class:

64.01.01.03 (64)Cyclosilicates

(64.01)Cyclosilicate Rings with Other Anions and Insular Silicate Groups with mixed ring types

(64.01.01)Eudialyte Group

64.01.01.01 Eudialyte Na4(Ca,Ce)2(Fe,Mn,Y)ZrSi8O22(OH,Cl)2(?) R 3m 3 2/m

64.01.01.02 Alluaivite Na19(Ca,Mn)6(Ti,Nb)3(Si3O9)2(Si10O28)2Cl•2(H2O) R 3m 3 2/m

64.01.01.03 Kentbrooksite! (Na,REE)15(Ca,REE)6MnZr3NbSi25O74F2•2(H2O) R 3m 3m

64.01.01.04 Khomyakovite! Na12Sr3Ca6Fe3Zr3W(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3m 3m

64.01.01.05 Manganokhomyakovite! Na12Sr3Ca6Mn3Zr3W(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3m 3m

64.01.01.06 Oneillite! Na15Ca3Mn3Fe3Zr3Nb(Si25O73)(O,OH,H2O)3(OH,Cl)2 R 3 3

64.01.01.07 Ferrokentbrooksite! Na15Ca6(Fe,Mn)3Zr3NbSi25O73(O,OH,H2O)3(Cl,F,OH)2 R 3m 3m

64.01.01.08 Ikranite! (Na,H3O)15(Ca,Mn,REE)6Fe2Zr3([],Zr)([],Si)Si24O66(O,OH)6Cl•2-3H2O R 3m 3m

64.01.01.09 Feklichevite! Na11Ca9(Fe,Fe)2Zr3Nb[Si25O73](OH,H2O,Cl,O)5 R 3m 3m

64.01.01.10 Rastsvetaevite! Na27K8Ca12Fe3Zr6Si52O144(O,OH,H2O)6Cl2 R 3m 3m

64.01.01.11 Taseqite! Na12Sr3Ca6Fe3Zr3NbSi25O73(O,OH,H2O)3Cl2 R 3m 3m

64.01.01.12 Carbokentbrooksite! (Na,[])12(Na,Ce)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)•H2O R 3m 3m

64.01.01.13 Zirsilite-(Ce)! (Na,[])12(Ce,Na)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)•H2O R 3m 3m

64.01.01.14 Labyrinthite! (Na,K,Sr)35Ca12Fe3Zr6TiSi51O144(O,OH,H2O)9Cl3 R 3m 3m

64.01.01.15 Aqualite! (H3O)8(Na,K,Sr)5Ca6Zr3Si26O66(OH)9Cl R 3m 3m

64.01.01.16 Raslakite! Na15Ca3Fe3(Na,Zr)3Zr3(Si,Nb)(Si25O73)(OH,H2O)3(Cl,OH) R 3m 3m

64.01.01.17 Georgbarsanovite! Na12(Mn,Sr,REE)3Ca6Fe3Zr3NbSi25O76Cl2•H2O R 3m 3m

64.01.01.18 Johnsenite-(Ce)! Na12(Ce,REE,Sr)3Ca6Mn3Zr3W(Si25O73)(CO3)(OH,Cl)2 R 3m 3m

64.01.01.19 Golyshevite! (Na,Ca)10Ca9(Fe,Fe)2Zr3NbSi25O72(CO3)(OH)3•H2O R 3m 3m

64.01.01.20 Mogovidite! Na9(Ca,Na)6Ca6Fe2Zr3[]Si25O72(CO3)(OH)4 R 3m 3m

64.01.01.21 Dualite! Na30(Ca,Na,Ce,Sr)12(Na,Mn,Fe,Ti)6Zr3Ti3MnSi51O144(OH,H2O,Cl)9 R 3m 3m

64.01.01.22 Voronkovite! Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl•H2O R 3 3

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

References:

NAME( MinRec) PHYS. PROP.(Eur. J. Min.,Vol.10,p207-219,1998) OPTIC PROP.(MinRec)

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
13 - WWW-MINCRYST

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

Kentbrooksite

(Na,REE)15(Ca,REE)6Mn++Zr3NbSi25O74F2•2(H2O)
Dana No: 64.01.01.03 Strunz No: 09.CO.10
Locality:

Notes: