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 % K2 O
Cadmium 9.35 % Cd 10.68 % CdO
Copper 26.44 % Cu 33.09 % CuO
Arsenic 31.17 % As 47.81 % As2 O5
Hydrogen 0.50 % H 4.50 % H2 O
Oxygen 29.29 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
KCdCu5 (AsO4 )4 (As(OH)2O2)•2(H2 O)
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
X Ray Diffraction:
By Intensity(I/Io ): 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:
PEAndyrobertsite = 58.24 barns/electronU=PEAndyrobertsite 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 � 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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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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