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Stillwellite-(Ce) Mineral Data

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General Stillwellite-(Ce) Information

Help on Chemical  Formula: Chemical Formula: (Ce,La,Ca)BSiO5
Help on Composition: Composition: Molecular Weight = 245.85 gm
   Calcium     0.33 %  Ca    0.46 % CaO
   Lanthanum  16.95 %  La   19.88 % La2O3
   Cerium     28.50 %  Ce   33.38 % Ce2O3
   Silicon    11.42 %  Si   24.44 % SiO2
   Boron       4.40 %  B    14.16 % B2O3
   Neodymium   5.87 %  Nd    6.84 % Nd2O3
   Oxygen     32.54 %  O
             ______        ______ 
             100.00 %       99.15 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ce0.5La0.3Nd0.1Ca0.02BSiO5
Help on Environment: Environment: Metasomatic replacement of metamorphosed calcareous sediments and alkalic pegmatites in syenite.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1955
Help on Locality: Locality: Mary Kathleen mine, 55 km east of Mt. Isa, Queensland, Australia. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Frank Leslie Stillwell (1888-1963), Australian ore mineralogist and the dominant Ce content.
Help on Name Pronunciation: Name Pronunciation: Stillwellite-(Ce) + Pronunciation Say STILLWELLITE-(CE)
Help on Synonym: Synonym: ICSD 67685
  PDF 26-349
 

Stillwellite-(Ce) Image

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  Stillwellite-(Ce)

Comments: Brownish red euhedral crystal of stillwellite-(Ce) in matrix under halogen or sunlight lighting. Inset image shows the yellow color-change under fluorescent lighting.
Location: Darai -Piez Massif, Alay Range of Tien-Shan' Mountains, Garm Region, Tajikistan. Scale: Crystal Size 1.3 cm.
© Rob Lavinsky

Stillwellite-(Ce) Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:0.97895
Help on Cell Dimensions: Cell Dimensions: a = 6.844, c = 6.7, Z = 3; V = 271.79 Den(Calc)= 4.51
Help on Crystal System: Crystal System: Trigonal - Pyramidal H-M Symbol (3) Space Group: P 31
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.943(1), 3.445(0.9), 4.48(0.9),
 

Physical Properties of Stillwellite-(Ce)

Help on Cleavage: Cleavage: {???} Imperfect
Help on Color: Color: Red brown, Pale pink.
Help on Density: Density: 4.57 - 4.6, Average = 4.58
Help on Diaphaneity: Diaphaneity: Transparent to Translucent
Help on Fracture: Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Help on Habit: Habit: Massive - Uniformly indistinguishable crystals forming large masses.
Help on Habit: Habit: Rhombohedral Crystals - Occurs as well-formed crystals showing rhobohedral crystals.
Help on Hardness: Hardness: 6.5 - Pyrite
Help on Luster: Luster: Resinous
Help on Streak: Streak: white
 

Optical Properties of Stillwellite-(Ce)

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.005 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1727,KPDmeas= 0.1699,KC= 0.1691
Ncalc = 1.76 - 1.78
Help on Optical Data: Optical Data: Uniaxial (+), w=1.765-1.784, e=1.78-1.787, bire=0.0030-0.0150.
 

Calculated Properties of Stillwellite-(Ce)

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=4.16 gm/cc
note: Specific Gravity of Stillwellite-(Ce) =4.59 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.02
Boson Index = 0.98
Help on Photoelectric: Photoelectric: PEStillwellite-(Ce) = 259.85 barns/electron
U=PEStillwellite-(Ce) x relectron=1,080.70 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 49,647.95 (Gamma Ray American Petroleum Institute Units)
Concentration of Stillwellite-(Ce) per GRapi unit = 20.14 (PPM)

Stillwellite-(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) 612.65 ±153.16 grams of pure Stillwellite-(Ce) .

Estimated Radioactivity from Stillwellite-(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 / 7.47 cm 1,149,426 3.11E-05 49,647.95 16.32
100 gm / 3.47 cm 114,943 3.11E-06 4,964.79 1.63
10 gm / 1.61 cm 11,494 3.11E-07 496.48 0.16
1 gm / 7.47 mm 1,149 3.11E-08 49.65 0.02
0.1 gm / 3.47 mm 115 3.11E-09 4.96 0.00
0.01 gm / 1.61 mm 11 3.11E-10 0.50 0.00
0.001 gm / 0.75 mm 1 3.11E-11 0.05 0.00

Weight of pure Stillwellite-(Ce) in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.59 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 ( 2.57 % Th) From Sum REE Elements (51.31 % REE)
 

Stillwellite-(Ce) Classification

Help on  Dana Class: Dana Class: 54.02.03.02 (54)Nesosilicate Borosilicates and Some Beryllosilicates
  (54.02)with B in [4] coordination
  (54.02.03)Cappellanite - Stillwellite group
 
54.02.03.01 Cappelenite-(Y) Ba(Y,Ce)6Si3B6O24F2 P 3 3
 
54.02.03.02 Stillwellite-(Ce) (Ce,La,Ca)BSiO5 P 31 3
Help on  Strunz Class: Strunz Class: 09.AJ.25 09 - SILICATES (Germanates)
  09.A - Nesosilicates
  09.AJ -Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra,
 
09.AJ.25 Stillwellite-(Ce) (Ce,La,Ca)BSiO5 P 31 3
 

Other Stillwellite-(Ce) Information

Help on References: References: NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(AntBidBlaNic2)
Help on See Also: See Also: Links to other databases for Stillwellite-(Ce) :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Print or Cut-and-Paste your Stillwellite-(Ce) Specimen Label here :

Stillwellite-(Ce)

(Ce,La,Ca)BSiO5
Dana No: 54.02.03.02 Strunz No: 09.AJ.25
Locality:

 

Notes:

 

 
   
 


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