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 1100 °C
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.