Copper(II) arsenate

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Copper(II) arsenate
CAS number 7778-41-8 YesY
PubChem 26065
ChemSpider 24279 YesY
Jmol-3D images Image 1
Molecular formula Cu3(AsO4)2
Molar mass 468.48 g/mol
Appearance blue or bluish green powder
Density 5.2 g/cm3
Melting point 1,100 °C (2,010 °F; 1,370 K)
Solubility in water insoluble
Solubility soluble in ammonia, dilute acids
EU Index Not listed
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Copper arsenate (Cu3(AsO4)2.4H2O, or Cu5H2(AsO4)4.2H2O), also called copper orthoarsenate, tricopper arsenate, cupric arsenate, or tricopper orthoarsenate, is a blue or bluish-green powder insoluble in water and alcohol and soluble in aqueous ammonium and dilute acids. Its CAS number is 7778-41-8 or 10103-61-4.


Copper arsenate is an insecticide used in agriculture. It is also used as a herbicide, fungicide, and a rodenticide. It is also used as a poison in slug baits.

Copper arsenate can also be a misnomer for copper arsenite, especially when meant as a pigment.

Natural occurrences[edit]

Anhydrous copper arsenate, Cu3(AsO4)2, is found in nature as the mineral lammerite.[1] Copper arsenate tetrahydrate, Cu3(AsO4)2.4H2O, occurs naturally as the mineral rollandite.[2]

Related compounds[edit]

Copper arsenate hydroxide or basic copper arsenate (Cu(OH)AsO4) is a basic variant with CAS number 16102-92-4. It is found naturally as the mineral olivenite. It is used as an insecticide, fungicide, and miticide. Its use is banned in Thailand since 2001.[1]

See also[edit]

External links[edit]


  1. ^ Hawthorne, F. C. (1986). "Lammerite, Cu3(AsO4)2, a modulated close-packed structure". American Mineralogist 71: 206–209. 
  2. ^ Sarp, H.; Černý, R. (2000). "Rollandite, Cu3(AsO4)2·4H2O, a new mineral". Eur. J. Mineral. 12: 1045–1050. doi:10.1127/0935-1221/2000/0012-1045.