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Cornwallite

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Formula:
Cu5(AsO4)2(OH)4
System:
Monoclinic
Colour:
Verdigis green, ...
Hardness:
Name:
Named in 1846 by František Xaver Maximilian Zippe after Cornwall, England, wherein lies the type locality.
Dimorph of:
Isostructural with:
The arsenate analogue of pseudomalachite.
The monoclinic dimorph of cornubite.

A secondary mineral formed by the oxidation of ore containing both copper and arsenic (e.g, tennantite).

Classification of Cornwallite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
8.BD.05

8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
D : With only medium-sized cations, (OH, etc.):RO4= 2:1
41.4.2.2

41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
4 : (AB)5(XO4)2Zq
20.1.4

20 : Arsenates (also arsenates with phosphate, but without other anions)
1 : Arsenates of Cu
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First Recorded Occurrence of Cornwallite

Place of Conservation of First Recorded Material:
The Natural History Museum, London, England, MI 1985,1754.
Year of Discovery:
1846
Geological Setting of First Recorded Material:
Copper bearing sulfide veins

Occurrences of Cornwallite

Geological Setting:
Found in the oxidized zones of copper deposits.

Physical Properties of Cornwallite

Sub-Vitreous, Resinous, Waxy, Greasy
Diaphaneity (Transparency):
Translucent, Opaque
Comment:
Satiny or rough on surfaces from terminations of minute crystals.
Colour:
Verdigis green, blackish-green, emerald-green; emerald-green in transmitted light.
Streak:
Apple green
Hardness (Mohs):
Tenacity:
Brittle
Cleavage:
Distinct/Good
On one direction.
Fracture:
Irregular/Uneven, Conchoidal
Density:
4.17 g/cm3 (Measured)    4.64 g/cm3 (Calculated)

Crystallography of Cornwallite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Space Group Setting:
P21/a
Cell Parameters:
a = 17.33Å, b = 5.82Å, c = 4.60Å
β = 92.22°
Ratio:
a:b:c = 2.978 : 1 : 0.79
Unit Cell Volume:
V 463.61 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Microcrystalline, radial fibrous botyroidal to globular and vitreous crusts. Less common as rounded tabular to blocky crystals.
X-Ray Powder Diffraction Data:
d-spacingIntensity
4.60 (80)
3.53 (90)
3.22 (100)
3.10 (90)
3.02 (80)
2.478 (80)
2.414 (90)

Optical Data of Cornwallite

Type:
Biaxial (+/-)
RI values:
nα = 1.810 - 1.820 nβ = 1.815 - 1.860 nγ = 1.850 - 1.880
2V:
Measured: 30° to 50°, Calculated: 34°
Birefringence:
0.050
Max Birefringence:
δ = 0.040 - 0.060
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
r > v

Chemical Properties of Cornwallite

Formula:
Cu5(AsO4)2(OH)4
Essential elements:
All elements listed in formula:

Relationship of Cornwallite to other Species

Series:
Forms a series with Pseudomalachite (see here)
8.BD.05PseudomalachiteCu5(PO4)2(OH)4
8.BD.05ReichenbachiteCu5(PO4)2(OH)4
8.BD.10ArsenoclasiteMn52+(AsO4)2(OH)4
8.BD.10GatehouseiteMn52+(PO4)2(OH)4
8.BD.15ParweliteMn10Sb2As2Si2O24
8.BD.20ReppiaiteMn52+(VO4)2(OH)4
8.BD.25LudjibaiteCu5(PO4)2(OH)4
8.BD.30CornubiteCu5(AsO4)2(OH)4
20.1.1LammeriteCu3(AsO4)2
20.1.2OliveniteCu2(AsO4)(OH)
20.1.3ClinoclaseCu3(AsO4)(OH)3
20.1.5CornubiteCu5(AsO4)2(OH)4
20.1.6Chlorotile (of Frenzel)
20.1.7GeminiteCu(HAsO4) · H2O
20.1.8EuchroiteCu2(AsO4)(OH) · 3H2O
20.1.9StrashimiriteCu8(AsO4)4(OH)4 · 5H2O
20.1.10ArhbariteCu2Mg(AsO4)(OH)3
20.1.11LindackeriteCuCu4(AsO4)2(HAsO4)2 · 8-9H2O
20.1.12ConichalciteCaCu(AsO4)(OH)
20.1.13LiroconiteCu2Al(AsO4)(OH)4 · 4H2O
20.1.14CeruleiteCu2Al7(AsO4)4(OH)13 · 11.5H2O
20.1.15ChenevixiteCu2Fe23+(AsO4)2(OH)4
20.1.16ArthuriteCuFe23+(AsO4)2(OH)2 · 4H2O

Other Names for Cornwallite

Name in Other Languages:
German:Cornwallit
Simplified Chinese:翠绿砷铜矿
Spanish:Cornwallita
Traditional Chinese:翠綠砷銅礦

Other Information

Other Information:
Soluble in nitric acid.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Cornwallite

Reference List:
Haidinger (1828) Annalen der Physik, Halle, Leipzig: 14: 228 (as Erinite).

Haidinger (1828) Philosophical Magazine and Journal of Science: 4: 154 (as Erinite).

Turner (1828) Philosophical Magazine and Journal of Science: 4: 155.

Zippe, F. X. M. (1847): Über den Cornwallit, eine neue Species des Mineralreichs. Abhandlungen der Königlichen Böhmischen Gesellschaft der Wissenschaften 4, 649-654.

Greg, R.P. and Lettsom, W.G. (1858) Manual of the Mineralogy of Great Britain and Ireland. 483pp., London: 321.

Church (1868) Journal of the Chemical Society, London: 21: 276.

Hillebrand and Washington (1888) American Journal of Science: 35: 299.

Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 63, 72.

Berry, L.G. (1951) Observations on conichalcite, cornwallite, euchroite liroconite and olivenite. American Mineralogist: 36: 484–503.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 798-799 (as Erinite), 925.

Claringbull, G.F., M.H. Hey, and R.J. Davis (1959) Cornubite, a new mineral dimorphous with cornwallite. Mineralogical Magazine: 32: 1–5.

Neues Jahrbuch für Mineralogie, Monatshefte (1999): 468-480.

Anthony, J.W., Bideaux, R.A., Bladh, K.W., and Nichols, M.C. (2000) Handbook of Mineralogy, Volume IV. Arsenates, Phosphates, Vanadates. Mineral Data Publishing, Tucson, AZ, 680pp.: 129.

Internet Links for Cornwallite

Specimens:
The following Cornwallite specimens are currently listed for sale on minfind.com.

Localities for Cornwallite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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