Cornwallite Mineral Data

General Cornwallite Information

Chemical Formula: Cu5(AsO4)2(OH)4 Composition: Molecular Weight = 681.61 gm    Copper    46.61 %  Cu   58.35 % CuO    Arsenic   21.98 %  As   33.72 % As₂O₅    Hydrogen   0.89 %  H     7.93 % H₂O    Oxygen    30.51 %  O             ______        ______              100.00 %      100.00 % = TOTAL OXIDE Empirical Formula: Cu₅(AsO₄)₂(OH)₄•(H₂O) Environment: Dimorphous with cornubite. IMA Status: Valid Species (Pre-IMA) 1847 Locality: Link to MinDat.org Location Data. Name Origin: Named after the English leader Cornwall. Name Pronunciation: Cornwallite + Pronunciation Synonym: Erinite   ICSD 89035   PDF 39-1357  

Cornwallite Image

Images:

Cornwallite Crystallography

X Ray Diffraction: By Intensity(I/I_o): 3.22(1), 3.1(0.9), 3.53(0.9), Crystal Structure:

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Arlt T , Armbruster T , Neues Jahrbuch fur Mineralogie, Monatshefte , 1999 (1999) p.468-480, Single-crystal X-ray structure refinement of cornwallite, Cu5(AsO4)2(OH)4:, A comparison with its polymorph cornubite and the (PO4)-analogue pseudomalachite, Locality: Clara mine, Oberwolfach, Black Forest, Germany, Note: Biso for O2 and O4 switched to match calculated values

 

Physical Properties of Cornwallite

Color: Light green, Dark green, Black green.  

Optical Properties of Cornwallite

Gladstone-Dale: CI meas= -0.119 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.064 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1692,KPDmeas= 0.2024,KC= 0.1808
Ncalc = 1.72 - 1.88  

Calculated Properties of Cornwallite

Electron Density: Bulk Density (Electron Density)=4.60 gm/cc
note: Specific Gravity of Cornwallite =4.88 gm/cc.
Fermion Index: Fermion Index = 0.0001478015
Boson Index = 0.9998521985 Photoelectric: PE_Cornwallite = 35.97 barns/electron
U=PE_Cornwallite x rElectron Density= 165.32 barns/cc.
Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cornwallite is Not Radioactive  

Cornwallite Classification

Dana Class: 41.04.02.02 (41)Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen   (41.04)where (A B)5 (XO4)2 Zq   (41.04.02)Dana Group  

41.04.02.01 Cornubite Cu5(AsO4)2(OH)4 P1 1

 

41.04.02.02 Cornwallite Cu5(AsO4)2(OH)4 P 2₁/a 2/m

Strunz Class: 08.BD.05 08 - PHOSPHATES, ARSENATES, VANADATES   08.B - Phosphates, etc. with Additional Anions, without H2O   08.BD -With only medium-sized cations, (OH, etc.):RO4 = 2:1  

08.BD.05 Cornwallite Cu5(AsO4)2(OH)4 P 2₁/a 2/m

 

08.BD.05 Pseudomalachite Cu5(PO4)2(OH)4 P 2₁/a 2/m

 

08.BD.05 Reichenbachite Cu5(PO4)2(OH)4 P 2₁/a 2/m

 

Other Cornwallite Information

See Also: Links to other databases for Cornwallite :
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
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Ask about Cornwallite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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