Copper(II) arsenate

  (Redirected from Lammerite)

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(II) arsenate
IUPAC name
Copper(II) arsenate
Other names
Copper arsenate
3D model (JSmol)
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 soluble in ammonia, dilute acids
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1 mg/m3 (as Cu)[1]
REL (Recommended)
TWA 1 mg/m3 (as Cu)[1]
IDLH (Immediate danger)
TWA 100 mg/m3 (as Cu)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references


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 occurrencesEdit

Anhydrous copper arsenate, Cu3(AsO4)2, is found in nature as the mineral lammerite.[2] Copper arsenate tetrahydrate, Cu3(AsO4)2·4H2O, occurs naturally as the mineral rollandite.[3]

Related compoundsEdit

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.[4]

See alsoEdit


  1. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ Hawthorne, F. C. (1986). "Lammerite, Cu3(AsO4)2, a modulated close-packed structure" (PDF). American Mineralogist. 71: 206–209.
  3. ^ 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.
  4. ^ "Archived copy". Archived from the original on 2005-11-22. Retrieved 2006-01-14.CS1 maint: archived copy as title (link)

External linksEdit