Weeksite Mineral Data

General Weeksite Information

Chemical Formula:

K2(UO2)2Si6O15•4(H2O)

Composition:

Molecular Weight = 1,028.91 gm

Potassium 4.18 % K 5.04 % K₂O

Barium 4.00 % Ba 4.47 % BaO

Calcium 0.39 % Ca 0.55 % CaO

Uranium 48.58 % U 55.11 % UO₂

Silicon 13.65 % Si 29.20 % SiO₂

Hydrogen 0.27 % H 2.45 % H₂O

Oxygen 28.92 % O

______ ______

100.00 % 96.81 % = TOTAL OXIDE

Empirical Formula:

K_1.1Ba_0.3Ca_0.1(UO₂)_2.1Si₅O₁₃•1.4(H₂O)

Environment:

In "opal" veinlets in rhyolite and agglomerates, as well as in sandstones and limestones.

IMA Status:

Approved IMA 1960

Locality:

Autunite No. 8 claim, Thomas Range, Juab County, Utah, USA. Link to MinDat.org Location Data.

Name Origin:

Named for Mary Alice Dowse Weeks (1909-1988), mineralogist with the U.S. Geological Survey, noted specialist in the mineralogy of uranium and vanadium.

Name Pronunciation:

Weeksite

Synonym:

ICSD 63515

PDF 12-462

Weeksite Image

Images:

Weeksite

Comments: Bright yellow weeksite aggregates.
Location: Anderson mine, Yavapai County, Arizona, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Weeksite

Comments: Globular masses of yellow weeksite crystals with white aragonite on a sandstone matrix.
Location: Jackpile Mine, Laguna District, Cibola County, New Mexico, USA. Scale: Picture size 1 cm.
© Paul M. Schumacher

Weeksite Crystallography

Axial Ratios:

a:b:c =0.9972:1:2.5174

Cell Dimensions:

a = 14.209, b = 14.248, c = 35.869, Z = 16; V = 7,261.67 Den(Calc)= 3.76

Crystal System:

Orthorhombic - DipyramidalH-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): 7.11(1), 5.57(0.9), 8.98(0.8),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

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 Weeksite
[1]

Physical Properties of Weeksite

Cleavage:

{hk0} Distinct, {hk0} Distinct

Color:

Yellow.

Density:

4.1

Diaphaneity:

Transparent to Translucent

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Bladed - Aggregates of thin lath-like crystals (e.g. kyanite).

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

1-2 - Between Talc and Gypsum

Luminescence:

Radioactive.

Luster:

Waxy

Streak:

yellow

Optical Properties of Weeksite

Gladstone-Dale:

CI meas= -0.041 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.136 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.16,KPDmeas= 0.1467,KC= 0.1409
Ncalc = 1.53 - 1.58

Optical Data:

Biaxial (-), a=1.596, b=1.603, g=1.606, bire=0.0100, 2V(Calc)=66, 2V(Meas)=~60. Dispersion r > v strong.

Pleochroism (x):

colorless.

Pleochroism (y):

pale yellow green.

Pleochroism (z):

yellow green.

Calculated Properties of Weeksite

Electron Density:

Bulk Density (Electron Density)=3.62 gm/cc
note: Specific Gravity of Weeksite =4.10 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Weeksite=1,266.86 barns/electron
U=PE_Weeksite x r_electron=4,588.80 barns/cc.

Radioactivity:

GRapi = 3,658,435.27 (Gamma Ray American Petroleum Institute Units)
Concentration of Weeksite per GRapi unit = 273.34 (PPB)

Weeksite 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) 8.31 ± 2.08 grams of pure Weeksite .
Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 100 cm box) 831.41 ±207.85 grams of pure Weeksite .

**Estimated Radioactivity from Weeksite** - 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 / 7.75 cm	86,962,009	2.35E-03	3,658,435.27	1,202.77
100 gm / 3.60 cm	8,696,201	2.35E-04	365,843.53	120.28
10 gm / 1.67 cm	869,620	2.35E-05	36,584.35	12.03
1 gm / 7.75 mm	86,962	2.35E-06	3,658.44	1.20
0.1 gm / 3.60 mm	8,696	2.35E-07	365.84	0.12
0.01 gm / 1.67 mm	870	2.35E-08	36.58	0.01
0.001 gm / 0.78 mm	87	2.35E-09	3.66	0.00

Weight of pure Weeksite in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.10 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

Weeksite Classification

Dana Class:

53.03.02.01 (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 Weeksite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2, AmMin, Vol 86, p 1115) OPTIC PROP.(AntBidBlaNic2)

See Also:

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

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

Weeksite

K2(UO2)2Si6O15•4(H2O)
Dana No: 53.03.02.01 Strunz No: 09.AK.30
Locality:

Notes: