Marecottite Mineral Data

General Marecottite Information

Chemical Formula:

Mg3(H2O)18[(UO2)4O3(SO4)2]2•10(H2O)

Composition:

Molecular Weight = 3,310.81 gm

Magnesium 1.31 % Mg 2.18 % MgO

Uranium 59.24 % U 67.20 % UO₂

Manganese 0.96 % Mn 1.24 % MnO

Hydrogen 1.77 % H 15.79 % H₂O

Sulfur 3.85 % S 9.60 % SO₃

Oxygen 32.87 % O

______ ______

100.00 % 96.02 % = TOTAL OXIDE

Empirical Formula:

Mg_1.79Mn²⁺_0.58(UO₂)_8.24(SO₄)_3.97(OH)₂O_5.64ï¿½28.02(H₂O)

Environment:

Secondary mineral formed at low pH (<5) from the oxidation of sulfides in uranium-bearing deposits. (zippeite group; structure)

IMA Status:

Approved IMA 2003 (Dana # Added)

Locality:

La Creusaz U-prospect near Les Marecottes, Western Swiss Alps, Switzerland. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

IMA2001-056

Marecottite Image

Images:

Marecottite

Comments: SEM image of a typical marecottite aggregate. Note the perfect cleavage along (011) and the trace of the twin composition plane (arrow). (AmMin, v 88, p 678).
Location: La Creusaz, Swiss Alps. Scale: See Image.
© American Mineralogist

Images:

Magnesiozippeite Marecottite

Comments: Powdery and crystalline aggregates of red-brown marecottite and yellow magnesiozippeite on matrix.
Location: Svornost Mine, Jachymov, Bohemia, Czech Republic. Scale: Specimen Size 6.5x9 cm.
© Diederik Visser

Marecottite Crystallography

Axial Ratios:

a:b:c =0.9614:1:1.2313

Cell Dimensions:

a = 10.815, b = 11.249, c = 13.851, Z = 1; alpha = 66.224°, beta = 72.412°, gamma = 69.95° V = 1,380.89 Den(Calc)= 3.98

Crystal System:

Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 9.47(1)(011), 3.44(0.8)(013), 4.74(0.8)(022),3.38(0.7)(022), 2.876(0.3)(303), 3.07(0.2)(301), 3.11(0.2)(004), 3.16(0.2)(033), 6.29(0.2)(

Physical Properties of Marecottite

Cleavage:

{011} Perfect

Color:

Yellow orange.

Density:

4.03

Diaphaneity:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

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

Habit:

Rosette - Bundled tabular aggregates resembling rose flower petals.

Habit:

Triangular Crystals - Occurs as triangular shaped crystals.

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

cololess

Optical Properties of Marecottite

Gladstone-Dale:

CI meas= -0.273 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.326 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1919,KPDmeas= 0.1842,KC= 0.1447
Ncalc = 1.56 - 1.58

Optical Data:

Biaxial (?), a=1.735, g=1.75, bire=0.0150

Calculated Properties of Marecottite

Electron Density:

Bulk Density (Electron Density)=3.55 gm/cc
note: Specific Gravity of Marecottite =4.03 gm/cc.

Fermion Index:

Fermion Index = 0.0060282187
Boson Index = 0.9939717813

Photoelectric:

PE_Marecottite=1,524.76 barns/electron
U=PE_Marecottite x r_electron=5,418.64 barns/cc.

Radioactivity:

GRapi = 4,452,864.45 (Gamma Ray American Petroleum Institute Units)
Concentration of Marecottite per GRapi unit = 224.57 (PPB)

Marecottite 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) 6.83 ± 1.71 grams of pure Marecottite .
Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 100 cm box) 683.08 ±170.77 grams of pure Marecottite .

**Estimated Radioactivity from Marecottite** - 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 / 7.80 cm	106,041,448	2.87E-03	4,452,864.45	1,463.96
100 gm / 3.62 cm	10,604,145	2.87E-04	445,286.45	146.40
10 gm / 1.68 cm	1,060,414	2.87E-05	44,528.64	14.64
1 gm / 7.80 mm	106,041	2.87E-06	4,452.86	1.46
0.1 gm / 3.62 mm	10,604	2.87E-07	445.29	0.15
0.01 gm / 1.68 mm	1,060	2.87E-08	44.53	0.01
0.001 gm / 0.78 mm	106	2.87E-09	4.45	0.00

Weight of pure Marecottite in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.03 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

Marecottite Classification

Dana Class:

31.10.04.07 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.10)miscellaneous

(31.10.04)Zippeite Group

31.10.04.01 Zippeite K4(UO2)6(SO4)3(OH)10•4(H2O) C 2/m 2/m

31.10.04.02 Natrozippeite Na4(UO2)6(SO4)3(OH)10•4(H2O) Unk Ortho

31.10.04.03 Magnesiozippeite Mg(H2O)3.5(UO2)2(SO4)O2 C 2/m 2/m

31.10.04.04 Nickelzippeite Ni2(UO2)6(SO4)3(OH)10•16(H2O) Unk Ortho

31.10.04.05 Zinc-zippeite Zn2(UO2)6(SO4)3(OH)10•16(H2O) Unk Ortho

31.10.04.06 Cobaltzippeite Co2(UO2)6(SO4)3(OH)10•16(H2O) Unk Ortho

31.10.04.07 Marecottite! Mg3(H2O)18[(UO2)4O3(SO4)2]2•10(H2O) P1 1

31.10.04.08 Pseudojohannite! Cu6.5[(UO2)4O4(SO4)2]2(OH)5•25H2O P1 or P1 Tri

31.10.04.09 IMA2009-008 Y2[(UO2)8O6(SO4)4(OH)2]•26H2O P1 1

Strunz Class:

07.EC.15 07 - SULFATES (SELENATES, TELLURATES)

07.E - Uranyl Sulfates

07.EC -With medium-sized and large cations

07.EC.15 Marecottite! Mg3(H2O)18[(UO2)4O3(SO4)2]2•10(H2O) P1 1

Other Marecottite Information

References:

NAME( AmMin, 88:676) PHYS. PROP.(AmMin, 88:676) OPTIC PROP.(AmMin, 88:676)

See Also:

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

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Marecottite

Mg3(H2O)18[(UO2)4O3(SO4)2]2•10(H2O)
Dana No: 31.10.04.07 Strunz No: 07.EC.15
Locality:

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