Andyrobertsite Mineral Data

General Andyrobertsite Information

Chemical Formula:

KCdCu5(AsO4)4[As(OH)2O2]•2(H2O)

Composition:

Molecular Weight = 1,201.88 gm

Potassium 3.25 % K 3.92 % K₂O

Cadmium 9.35 % Cd 10.68 % CdO

Copper 26.44 % Cu 33.09 % CuO

Arsenic 31.17 % As 47.81 % As₂O₅

Hydrogen 0.50 % H 4.50 % H₂O

Oxygen 29.29 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

KCdCu₅(AsO₄)₄(As(OH)2O2)•2(H₂O)

Environment:

Single specimen found at the mine. Forms a series with calcioandyrobertsite.

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Tsumeb Mine, Tsumeb, Namibia. Link to MinDat.org Location Data.

Name Origin:

Named after Andrew C. Roberts (1950-), mineralogist with the Geological Survey of Canada, specialist in documentation of new mineral species, in particular from low-temperature seco ndary parageneses.

Name Pronunciation:

Andyrobertsite + Pronunciation

Synonym:

ICSD 89894

IMA1997-023

Andyrobertsite Image

Images:

Andyrobertsite

Comments: Blue andyrobertsite with blue calcioandyrobertsite on green olivenite. Holotype specimen Min Record cover.
Location: Tsumeb Mine, Tsumeb, Namibia.. Scale: Specimen 4.1 cm.
© William Pinch

Andyrobertsite Crystallography

Axial Ratios:

a:b:c =0.9776:1:0.9941

Cell Dimensions:

a = 9.81, b = 10.034, c = 9.975, Z = 2; beta = 101.84° V = 960.98 Den(Calc)= 4.15

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/m

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

By Intensity(I/I_o): 9.64(1), 3.145(0.5), 4.46(0.4),

Physical Properties of Andyrobertsite

Cleavage:

{100} Good

Color:

Electric blue.

Density:

4.011

Diaphaneity:

Transparent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

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

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

pale blue

Optical Properties of Andyrobertsite

Gladstone-Dale:

CI meas= -0.085 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.048 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1788,KPDmeas= 0.185,KC= 0.1706
Ncalc = 1.68 - 1.71

Optical Data:

Biaxial (-), a=1.72, b=1.749, g=1.757, bire=0.0370

Calculated Properties of Andyrobertsite

Electron Density:

Bulk Density (Electron Density)=3.86 gm/cc
note: Specific Gravity of Andyrobertsite =4.15 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_{Andyrobertsite}= 58.24 barns/electron
U=PE_{Andyrobertsite} x r_electron= 224.84 barns/cc.

Radioactivity:

GRapi = 43.68 (Gamma Ray American Petroleum Institute Units)
Concentration of Andyrobertsite per GRapi unit = 2.29 (%)

Estimated Radioactivity from Andyrobertsite - barely detectable

Andyrobertsite Classification

Dana Class:

42.09.02.03 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen

(42.09)where (A)3 (XO4)2 Zq ï¿½ x(H2O)

(42.09.02)Souzalite Group

42.09.02.01 Souzalite (Mg,Fe)3(Al,Fe)4(PO4)4(OH)6•2(H2O) P1,P 1 Tri

42.09.02.02 Gormanite Fe3Al4(PO4)4(OH)6•2(H2O) P1,P 1 Tri

42.09.02.03 Andyrobertsite! KCdCu5(AsO4)4[As(OH)2O2]•2(H2O) P 2₁/m 2/m

42.09.02.04 Calcioandyrobertsite-1M! KCaCu5(AsO4)4[As(OH)2O2]•2(H2O) P 2₁/m 2/m

42.09.02.05 Calcioandyrobertsite-2O! KCaCu5(AsO4)4[As(OH)2O2]•2(H2O) P nma 2/m 2/m 2/m

Strunz Class:

08.DH.50 08 - PHOSPHATES, ARSENATES, VANADATES

08.D - Phosphates, etc

08.DH -With large and medium-sized cations, (OH, etc.):RO4 < 1:1

08.DH.50 Andyrobertsite! KCdCu5(AsO4)4[As(OH)2O2]•2(H2O) P 2₁/m 2/m

08.DH.50 Calcioandyrobertsite-1M! KCaCu5(AsO4)4[As(OH)2O2]•2(H2O) P 2₁/m 2/m

08.DH.50 Calcioandyrobertsite-2O! KCaCu5(AsO4)4[As(OH)2O2]•2(H2O) P nma 2/m 2/m 2/m

Other Andyrobertsite Information

References:

NAME( MinRec, Vol 30) PHYS. PROP.(MinRec, Vol 30) OPTIC PROP.(MinRec, Vol 30)

See Also:

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

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

Andyrobertsite

KCdCu5(AsO4)4[As(OH)2O2]•2(H2O)
Dana No: 42.09.02.03 Strunz No: 08.DH.50
Locality:

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