Boltwoodite Mineral Data

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General Boltwoodite Information

Chemical Formula:

HK(UO2)(SiO4)•1.5(H2O)

Composition:

Molecular Weight = 429.24 gm

Potassium 9.11 % K 10.97 % K₂O

Uranium 55.45 % U 62.91 % UO₂

Silicon 6.54 % Si 14.00 % SiO₂

Hydrogen 0.94 % H 8.39 % H₂O

Oxygen 27.96 % O

______ ______

100.00 % 96.27 % = TOTAL OXIDE

Empirical Formula:

HK(UO₂)(SiO₄)•1.5(H₂O)

Environment:

In the outer silicate zone of alteration surrounding hydrated uranyl oxides incrusting primary uraninite; also filling fractures at some distance from primary uraninite.

IMA Status:

Valid Species (Pre-IMA) 1956

Locality:

In the USA, from the Delta mine, Emery Co., Utah; the New Method mine, near Amboy, San Bernardino Co., California. Link to MinDat.org Location Data.

Name Origin:

For Bertram Borden Boltwood (1870-1927), radiochemist of Yale University, New Haven, Connecticut, USA, who devised the U-Pb method of measuring geologic time.

Name Pronunciation:

Boltwoodite + Pronunciation

Synonym:

ICSD 86631

Nenadkevite

PDF 35-490

Boltwoodite Image

Images:

Boltwoodite

Comments: Sprays of boltwoodite covering matrix.
Location: Rossing, Namibia. Scale: Size Not Given.
© John Veevaert

Images:

Boltwoodite

Comments: Bright yellow, prismatic crystals of boltwoodite.
Location: Rössing mine, Swakopmund District, Namibia. Scale: Picture size 2.5 mm.
© Paul M. Schumacher

Images:

Boltwoodite

Comments: Yellow, globular aggregates of boltwoodite on a ferruginous matrix.
Location: Repete Mine, San Juan County, Utah, USA. Scale: See Image.
© Jeff Weissman / Photographic Guide to Mineral Species

Boltwoodite Crystallography

Axial Ratios:

a:b:c =1.9201:1:1.7296

Cell Dimensions:

a = 13.71, b = 7.14, c = 12.35, Z = 6; beta = 102.2° V = 1,181.63 Den(Calc)= 3.62

Crystal System:

Monoclinic - SphenoidalH-M Symbol (2) Space Group: P 2₁

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

By Intensity(I/I_o): 6.81(1), 3.4(0.9), 2.95(0.8),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
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Stohl F V , Smith D K , American Mineralogist , 66 (1981) p.610-625, The crystal chemistry of the uranyl silicate minerals

View Additional jPOWD Structure files for Boltwoodite
[1]

Physical Properties of Boltwoodite

Cleavage:

{010} Perfect, {001} Distinct

Color:

Yellow, Light yellow.

Density:

3.6

Hardness:

3.5-4 - Copper Penny-Fluorite

Luminescence:

Fluorescent, Short UV=dull green, Long UV=dull green.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Boltwoodite

Gladstone-Dale:

CI meas= -0.346 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.338 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1901,KPDmeas= 0.1912,KC= 0.1421
Ncalc = 1.51

Optical Data:

Biaxial (-), a=1.669, b=1.6955, g=1.7005, bire=0.0315

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Boltwoodite

Electron Density:

Bulk Density (Electron Density)=3.19 gm/cc
note: Specific Gravity of Boltwoodite =3.62 gm/cc.

Fermion Index:

Fermion Index = 0.0071947992
Boson Index = 0.9928052008

Photoelectric:

PE_Boltwoodite=1,429.97 barns/electron
U=PE_Boltwoodite x r_electron=4,558.55 barns/cc.

Radioactivity:

GRapi = 4,162,622.33 (Gamma Ray American Petroleum Institute Units)
Concentration of Boltwoodite per GRapi unit = 240.23 (PPB)

Boltwoodite 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) 7.31 ± 1.83 grams of pure Boltwoodite .
Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 100 cm box) 730.71 ±182.68 grams of pure Boltwoodite .

**Estimated Radioactivity from Boltwoodite** - very strong
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 / 8.08 cm	99,264,658	2.68E-03	4,162,622.33	1,368.53
100 gm / 3.75 cm	9,926,466	2.68E-04	416,262.23	136.85
10 gm / 1.74 cm	992,647	2.68E-05	41,626.22	13.69
1 gm / 8.08 mm	99,265	2.68E-06	4,162.62	1.37
0.1 gm / 3.75 mm	9,926	2.68E-07	416.26	0.14
0.01 gm / 1.74 mm	993	2.68E-08	41.63	0.01
0.001 gm / 0.81 mm	99	2.68E-09	4.16	0.00

Weight of pure Boltwoodite in grams (gm) and Calculated Diameter of a Sphere with a Density of 3.62 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

Boltwoodite Classification

Dana Class:

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

(53.03)with (UO2)

(53.03.01)Uranophane group

53.03.01.01 Kasolite Pb(UO2)SiO4•(H2O) P 2₁/a 2/m

53.03.01.02 Uranophane Ca(UO2)2SiO3(OH)2•5(H2O) P 2₁ 2

53.03.01.03 Sklodowskite (H3O)2Mg(UO2)2(SiO4)2•4(H2O) C 2/m 2/m

53.03.01.04 Cuprosklodowskite Cu[(UO2)(SiO2OH)]2•6(H2O) P1 1

53.03.01.05 Boltwoodite HK(UO2)(SiO4)•1.5(H2O) P 2₁ 2

53.03.01.06 Natroboltwoodite (H3O)(Na,K)(UO2)SiO4•(H2O) P 2₁2₁2₁ 2 2 2

53.03.01.07 Oursinite (Co,Mg)(H3O)2[(UO2)SiO4]2•3(H2O) Aba2,Abam Ortho

53.03.01.08 Swamboite UH6(UO2)6(SiO4)6•30(H2O) P 2₁/a 2/m

53.03.01.09 Uranophane-beta Ca[(UO2)SiO3(OH)]2•(H2O) P 2₁/a 2/m

Strunz Class:

09.AK.15 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AK -Uranyl neso- and polysilicates

09.AK.15 Boltwoodite HK(UO2)(SiO4)•1.5(H2O) P 2₁ 2

09.AK.15 Kasolite Pb(UO2)SiO4•(H2O) P 2₁/a 2/m

09.AK.15 Uranophane Ca(UO2)2SiO3(OH)2•5(H2O) P 2₁ 2

09.AK.15 Natroboltwoodite (H3O)(Na,K)(UO2)SiO4•(H2O) P 2₁2₁2₁ 2 2 2

Other Boltwoodite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Boltwoodite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - Philatelic Mineralogy
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - Scandinavian mineral gallery
18 - Uranium Minerals
19 - WWW-MINCRYST

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Ask about Boltwoodite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
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Print or Cut-and-Paste your Boltwoodite Specimen Label here :

Boltwoodite

HK(UO2)(SiO4)•1.5(H2O)
Dana No: 53.03.01.05 Strunz No: 09.AK.15
Locality:

Notes: