Rollandite Mineral Data

General Rollandite Information

Chemical Formula:

Cu3(AsO4)2•4(H2O)

Composition:

Molecular Weight = 543.29 gm

Copper 36.26 % Cu 45.39 % CuO

Arsenic 27.58 % As 42.31 % As₂O₅

Hydrogen 1.41 % H 12.60 % H₂O

Oxygen 34.75 % O

______ ______

100.00 % 100.29 % = TOTAL OXIDE

Empirical Formula:

Cu_3.1(AsO₄)₂•3.8(H₂O)

Environment:

Secondary mineral in old Cu mines. New structure-type.

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

Cu mines of Roua at the western margin of the Barrot Dome, Alpes-Maritimes, France. Link to MinDat.org Location Data.

Name Origin:

Named for Pierre Rolland (1940-), an eminent mineral collector of the Roua mines.

Synonym:

ICSD 90026

IMA1998-001

Rollandite Crystallography

Axial Ratios:

a:b:c =0.3335:1:0.5704

Cell Dimensions:

a = 5.6906, b = 17.061, c = 9.732, Z = 4; V = 944.85 Den(Calc)= 3.82

Crystal System:

Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: P nma

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

By Intensity(I/I_o): 8.52(1)(020), 3.221(0.9)(141,051), 3.721(0.6)(131),3.102(0.4)(132), 2.795(0.35)(142), 2.817(0.35)(103,033), 2.133(0.25)(080,251), 2.35(0.25)(143,053), 2.366(0.2)(240,071),

Forms:

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Forms: ( 0 1 0) ( 1 0 1) ( 1 0 0) ( 0 1 1) ( 0 0 1)

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Physical Properties of Rollandite

Cleavage:

{001} Good

Color:

Bottle green.

Density:

3.9

Diaphaneity:

Transparent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Hardness:

4-4.5 - Between Fluorite and Apatite

Luster:

Vitreous (Glassy)

Streak:

light green

Optical Properties of Rollandite

Gladstone-Dale:

CI meas= -0.025 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.046 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1972,KPDmeas= 0.1932,KC= 0.1885
Ncalc = 1.72 - 1.74

Optical Data:

Biaxial (-), a=1.745, b=1.755, g=1.76, bire=0.0150, 2V(Calc)=70, 2V(Meas)=71. Dispersion strong, r < v.

Calculated Properties of Rollandite

Electron Density:

Bulk Density (Electron Density)=3.70 gm/cc
note: Specific Gravity of Rollandite =3.90 gm/cc.

Fermion Index:

Fermion Index = 0.000168915
Boson Index = 0.999831085

Photoelectric:

PE_Rollandite= 34.93 barns/electron
U=PE_Rollandite x rElectron Density= 129.32 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Rollandite is Not Radioactive

Rollandite Classification

Dana Class:

40.03.04.02 (40)Hydrated Phosphates, etc

(40.03)where (A++)3 (XO4)2 ï¿½ x(H2O)

(40.03.04)Hopeite Group

40.03.04.01 Hopeite Zn3(PO4)2•4(H2O) P nma 2/m 2/m 2/m

40.03.04.02 Rollandite! Cu3(AsO4)2•4(H2O) P nma 2/m 2/m 2/m

Strunz Class:

08.CD.30 08 - PHOSPHATES, ARSENATES, VANADATES

08.C - Phosphates without Additional Anions, with H2O

08.CD -With only medium-sized cations, RO4:H2O = 1:2

08.CD.30 Rollandite! Cu3(AsO4)2•4(H2O) P nma 2/m 2/m 2/m

Other Rollandite Information

References:

NAME( AmMin, vol 86, p 768) PHYS. PROP.(AmMin, vol 86, p 768) OPTIC PROP.(AmMin, vol 86, p 768)

See Also:

Links to other databases for Rollandite :
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 - WWW-MINCRYST

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

Rollandite

Cu3(AsO4)2•4(H2O)
Dana No: 40.03.04.02 Strunz No: 08.CD.30
Locality:

Notes:

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