Crystal System: Orthorhombic
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Basic copper arsenate
Chemical Formula: Cu2(AsO4)(OH)
Method(s) of Verification: Gwaith-yr-Afon Mine - XRD at the Natural History Museum, London; Dolyhir Quarry - XRD at Manchester Museum and WDS at the Open University (analyses OU P202-P204, P377-P380).

Chemical Group:

  • Arsenates

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Pale green olivenite coating dark blue azurite within a cavity in limestone from Dolyhir Quarry. Photo by D.I. Green. © D.I. Green.
Crust of acicular olivenite microcrystals from Dolyhir Quarry. Neil Hubbard Collection. Photo D.I. Green, © D.I. Green.
Silky, white, acicular olivenite from Gwaith-yr-Afon Mine in the Central Wales Orefield. Specimen and photo S.A. Rust. © S.A. Rust.
Introduction: olivenite is a supergene mineral that is typically encountered in the oxidized zones of chalcopyrite and arsenopyrite-bearing hydrothermal veins, but can occur in any type of weathered copper-arsenic-bearing primary association. It is usually accompanied by other arsenates such as clinoclase, tyrolite, chalcophyllite, scorodite and pharmacosiderite.
Occurrence in Wales: only discovered in very small quantities in Wales. Olivenite is currently known from two localities. This is in stark contrast to some other UK mining districts - such as Cornwall, where it is widespread and common at some localities. This perhaps reflects the paucity of arsenic/copper-bearing mineral veins with well-developed oxidation zones in Wales.

Key Localities:

  • Dolyhir Quarry, Old Radnor, Powys: olivenite formerly occurred relatively commonly as sprays of minute pale green acicular crystals associated with azurite, tyrolite and zincolivenite. The occurrence was hosted by barite-calcite veins surrounding a large sulphide vein outcropping in Wenlock Limestone which was exposed at the quarry in the mid-1990s. The locality has since been quarried away but specimens have been preserved in the National Museum of Wales Collection (Cotterell et al., 2011).
  • Gwaith-yr-Afon Mine, Goginan, Ceredigion: two specimens of olivenite have been found at this locality, better known for the more conspicuous occurrence of tyrolite. It occurs as the white variety (known as "leucochalcite"), forming silky-textured radial crystal groups to 0.75 mm in diameter covering areas to a square centimetre or so on goethite-coated quartz (Rust & Mason, 1994).

There are no key localities for this specimen.


  1. Cotterell, T.F., Green, D.I., Hubbard, N., Mason, J.S., Starkey, R.E. and Tindle, A.G., 2011. The Mineralogy of Dolyhir Quarry, Old Radnor, Powys, Wales. UK Journal of Mines and Minerals, 32, 5-61.
  2. Rust, S.A. & Mason, J.S., 1994. An unusual occurrence of arsenate minerals at Gwaith-yr-Afon mine, Dyfed, Wales. Journal of the Russell Society, 5(2), 109-113.

There are no references for this specimen.