Coutinhoite Mineral Data

General Coutinhoite Information

Chemical Formula:

ThxBa1-2x(H2O)y(UO2)2Si5O13•H2O

Composition:

Molecular Weight = 2,118.94 gm

Potassium 0.13 % K 0.16 % K₂O

Barium 1.23 % Ba 1.37 % BaO

Calcium 0.08 % Ca 0.11 % CaO

Thorium 3.29 % Th 3.74 % ThO₂

Uranium 67.40 % U 76.46 % UO₂

Silicon 6.52 % Si 13.95 % SiO₂

Phosphorus 0.12 % P 0.27 % P₂O₅

Hydrogen 0.27 % H 2.43 % H₂O

Oxygen 20.97 % O

______ ______

100.00 % 98.49 % = TOTAL OXIDE

Empirical Formula:

Th_0.3Ba_0.19K_0.07Ca_0.043(UO₂)₂Si_4.92P_0.08O_12.91ï¿½2.86(H₂O)

Environment:

Secondary hydrothermal mineral in a pegmatite from the oxidation of uraninite. Isostructural with weeksite.

IMA Status:

Approved IMA 2004 (Dana # Added)

Locality:

Corrego do Urcum granitic pegmatite, Lavra Urucum, Galileia Co., Minas Gerais, Brazil. Link to MinDat.org Location Data.

Name Origin:

Named for Jose Moacyr Vianna Coutinho (1924-), Professor of Mineralogy and Petrography the the Instituto de Geociencieas of Universidad de Sao Paulo, Brazil.

Synonym:

IMA2003-025

Coutinhoite Image

Images:

Coutinhoite

Comments: New mineral, IMA 2003-025, from this pegmatite. This is a co-type specimen. Flaky crystals of choutinhoite to less than 0.25mm in gelatin capsule.
Location: Lavra do Urucum, Serra do Urucum, Galileia, Minas Gerais, Brazil. Scale: Crystal size 0.25mm.
© Tom Loomis / Dakota Matrix

Images:

Coutinhoite

Comments: Irregular aggregate of yellow coutinhoite. (AmMin, v 89, p 721).
Location: Urucum mine, GalilÃ©ia, Minas Gerais, Brazil. Scale: See Image.
© American Mineralogist

Coutinhoite Crystallography

Axial Ratios:

a:b:c =0.9981:1:2.519

Cell Dimensions:

a = 14.1676, b = 14.1935, c = 35.754, Z = 8; V = 7,189.69 Den(Calc)= 3.91

Crystal System:

Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: C mmb

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

By Intensity(I/I_o): 7.059(1)(020), 3.528(0.86)(040), 2.904(0.78)(2.2.10),3.188(0.73)(2.0.10), 5.563(0.59)(024), 3.287(0.57)(404), 4.581(0.47)(206), 2.981(0.46)(424),

Physical Properties of Coutinhoite

Color:

Yellow.

Diaphaneity:

Transparent to Translucent

Habit:

Flakes - Flat, thin crystals or aggregates.

Habit:

Scaly - Morphology like fish scales.

Hardness:

1.5 - Between Talc and Gypsum

Luster:

Waxy

Streak:

yellow

Optical Properties of Coutinhoite

Gladstone-Dale:

CI calc= -0.303 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1599,KC= 0.1228
Ncalc = 1.48

Optical Data:

Biaxial (-), a=1.62, b=1.627, g=1.629, bire=0.0090, 2V(Calc)=56, 2V(Meas)=40. Dispersion r < v strong.

Calculated Properties of Coutinhoite

Electron Density:

Bulk Density (Electron Density)=3.28 gm/cc
note: Specific Gravity of Coutinhoite =3.91 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Coutinhoite=1,909.34 barns/electron
U=PE_Coutinhoite x r_electron=6,269.44 barns/cc.

Radioactivity:

GRapi = 4,883,485.28 (Gamma Ray American Petroleum Institute Units)
Concentration of Coutinhoite per GRapi unit = 204.77 (PPB)

Coutinhoite 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) 6.23 ± 1.56 grams of pure Coutinhoite .
Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 100 cm box) 622.85 ±155.71 grams of pure Coutinhoite .

**Estimated Radioactivity from Coutinhoite** - very strong
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 / 7.88 cm	122,118,225	3.30E-03	4,883,485.28	1,605.53
100 gm / 3.66 cm	12,211,823	3.30E-04	488,348.53	160.55
10 gm / 1.70 cm	1,221,182	3.30E-05	48,834.85	16.06
1 gm / 7.88 mm	122,118	3.30E-06	4,883.49	1.61
0.1 gm / 3.66 mm	12,212	3.30E-07	488.35	0.16
0.01 gm / 1.70 mm	1,221	3.30E-08	48.83	0.02
0.001 gm / 0.79 mm	122	3.30E-09	4.88	0.00

Weight of pure Coutinhoite in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.91 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

Coutinhoite Classification

Dana Class:

53.03.02.04 (53)Nesosilicate Insular SiO4 Groups and Other Anions of Complex Cations

(53.03)with (UO2)

(53.03.02)Weeksite group

53.03.02.01 Weeksite K2(UO2)2Si6O15•4(H2O) C mmb 2/m 2/m 2/m

53.03.02.02 Haiweeite Ca[(UO2)2Si5O12(OH)2]•3(H2O) C mcm 2/m 2/m 2/m

53.03.02.03 Metahaiweeite Ca(UO2)2Si6O15•n(H2O),n<5 P 2/c ? 2/m

53.03.02.04 Coutinhoite! ThxBa1-2x(H2O)y(UO2)2Si5O13•H2O C mmb 2/m 2/m 2/m

Strunz Class:

09.AK.30 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AK -Uranyl neso- and polysilicates

09.AK.30 Weeksite K2(UO2)2Si6O15•4(H2O) C mmb 2/m 2/m 2/m

09.AK.30 Coutinhoite! ThxBa1-2x(H2O)y(UO2)2Si5O13•H2O C mmb 2/m 2/m 2/m

Other Coutinhoite Information

References:

NAME( AmMin, v 89, p 721) PHYS. PROP.(AmMin, v 89, p 721) OPTIC PROP.(AmMin, v 89, p 721)

See Also:

Links to other databases for Coutinhoite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info
11 - Uranium Minerals

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

Coutinhoite

ThxBa1-2x(H2O)y(UO2)2Si5O13•H2O
Dana No: 53.03.02.04 Strunz No: 09.AK.30
Locality:

Notes:

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