Olivenite

minerals

conichalcite

euchroite

mixite

Images
Formula: Cu2(AsO4)(OH)
Anhydrous arsenate containing hydroxyl, olivenite group, forms a series with libethenite and with adamite.
Specific gravity: 3.9 to 4.5
Hardness: 3
Streak: Olive-green to brown
Colour: Olive green to yellow or brown, grey-green, greyish white; light green in transmitted light.
Solubility: Soluble in acids and in ammonia
Common impurities: Fe,P
Environments:

Hydrothermal environments

Olivenite is a relatively common, thermodynamically very stable, secondary copper mineral found in the oxidised zones of copper deposits containing arsenic-bearing phases, especially tennantite and enargite (Mindat). It is the most common secondary copper arsenate in the oxdised zone of hydrothermal copper deposits.

Associated minerals include clinoclase, conichalcite, tyrolite, cornetite, cornwallite, metazeunerite, scorodite, pharmacosiderite, spangolite, chalcophyllite, brochantite, malachite, azurite and chrysocolla (HOM).

Localities

At the Block 14 open cut, Broken Hill, New South Wales, Australia, olivenite occurs with beudantite-segnitite, bayldonite, mawbyite and mimetite. Later sulphate minerals such as brochantite and linarite also occur on some specimens (AJM 3.1.54).

At the New Cobar deposit, New South Wales, Australia, olivenite occurs in vugs in quartz, associated with chenevixite and agardite, and almost always associated with partially oxidised arsenopyrite (AJM 11.2.80).

At the Desolation prospect, Mount Isa Block, Queensland, Australia, olivenite is found on chrysocolla, associated with clinoclase. Olivenite and libethenite also occur on earlier chrysocolla and As-rich pseudomalachite crusts (AJM 17.2.86).

At the Bali Lo prospect, Ashburton Downs, Western Australia, olivenite occurs intergrown with chenevixite (AJM 13.1.34-35).

At the Telfer gold mine, Western Australia, olivenite has been found radiating from cavity surfaces in quartz veins overgrown by chrysocolla (AJM 12.1.39).

At the Clara mine, Near Wolfach in the Black Forest, Germany, olivenite and its associated minerals agardite-(Ce), cornwallite and clinoclase, are perched on a fluorite and/or baryte matrix with disseminated tetrahedrite-tennantite. Also an olivenite-adamite solid solution is found associated with philipsburgite (R&M 90.1.45).

At Ightem, Bou Azzer, Morocco, zinc-rich olivenite occurs associated with powellite (MinRec 38.5.385).

At Tamdrost-West, Bou Azzer, Morocco, cobalt and nickel-rich olivenite has been found in cavities in quartz associated with pharmacosiderite (MinRec 38.5.385).

At Tsumeb, Namibia, olivenite occurs with azurite and malachite (R&M 93.6.546), and also with adamite, zincolivenite, duftite/conichalcite and arsentsumebite, often on quartz (R&M 95.3.210-232).

At Caldbeck Fells, Cumbria, England, UK, olivenite is rare. At Carrock mine and at Ingray Gill it occurs in cavities in quartz. At Dry Gill mine it has been found with beudantite, and at Old Potts mine it has been found with cornwallite and conichalcite (C&S).

At the San Rafael mine, Nye county, Nevada, USA, olivenite occurs within zones containing mixite and conichalcite in the rosasite stope. Olivenite has also been documented here in association with cornubite and cornwallite (R&M 85.6.520).

At the Majuba mine, Pershing county, Nevada, USA, olivenite is associated with cornetite (Dana).

At the Mammoth mines, Tintic district, Utah, USA, olivenite is associated with clinoclase, tyrolite and conichalcite (Dana).

Alteration

euchroite (s) to olivenite (s) and H2O (l)
Cu2AsO4(OH). 3H2O ⇌ Cu2AsO4(OH) + 3H2O
(MM 52.684)

The Activity-pH diagram below was calculated at 298.2 K for the main Cu2+ and Pb2+ arsenate minerals. Boundaries are calculated for constant activities (roughly equivalent to concentrations) of Pb2+ and Cl- ions in solution, over a range of values of pH and of Cu2+ activity. Higher chloride activites make the stability fields of bayldonite and duftite vanish, with respect to the encroachment of that of mimetite (LMW p269).
stability Cu Pb.jpg

The arsenate mineral formulae are:
philipsbornite PbAl3(AsO4)(AsO3OH)(OH)6
mimetite Pb5(AsO4)3Cl
duftite PbCu(AsO4)(OH)
bayldonite Cu3PbO(AsO3OH)2(OH)2
olivenite Cu2(AsO4)(OH)
cornwallite Cu5(AsO4)2(OH)4
clinoclase Cu3(AsO4)(OH)3












The Activity-pH diagram below was calculated at 298.2 K for some carbonates and copper arsenates for constant activity (roughly equivalent to concentration) of H2AsO4- in solution, over a range of values of pH and of H2CO3 activity (MM 52.687).
stability AsO4, CO3.jpg

The mineral formulae are:
azurite: Cu3(CO3)2(OH)2
malachite: Cu2(CO3)(OH)2
olivenite: Cu2(AsO4)(OH)
cornubite: Cu5(AsO4)2(OH)4
clinoclase: Cu3(AsO4)(OH)3













The Activity-pH diagram below was calculated at 298.2 K for some arsenates and sulphates for constant activity (roughly equivalent to concentration) of H2AsO4- in solution, over a range of values of pH and of SO42- activity (MM 52.689).
stability sulphates.jpg

The mineral formulae are:
chalcanthite: Cu(SO4).5H2O
antlerite: Cu2+3(SO4)(OH)4
brochantite: Cu4(SO4)(OH)6
olivenite: Cu2(AsO4)(OH)
cornubite: Cu5(AsO4)2(OH)4
clinoclase: Cu3(AsO4)(OH)3













Back to Minerals