Zincolivenite


Composition: CuZn(AsO4)(OH)
Crystal System : Orthorhombic
Colours: Green, greenish-blue
Lustre : Vitreous
Hardness (H) : 3.5
Specific Gravity (S.G) : 4.34

Distribution

Common. Occurs in all three oxidation zones.

Occurrence

  • Supergene
  • 1st Oxidation Zone
  • 2nd Oxidation Zone
  • 3rd Oxidation Zone

Notable Finds

The following discoveries of "cuproadamite" would almost certainly fall within the definition of zincolivenite: (1) In the second oxidation zone, Key (1977) recalls a major discovery on 28 Level, in c. 1973/74, that yielded a variety of arsenates including a complete gradation "between cuproadamite and zincian olivenite", of which most spectacular were dark olive green, blocky crystals to 35 mm, and prismatic emerald-green crystals with schultenite. (2) The 1986 pocket of cuprian adamite on bright yellow ferrilotharmeyerite from 30 Level in the second oxidation zone (see Gebhard, 1999; Cairncross, 2000) was arguably one of the most spectacular finds. (3) In the third oxidation zone, sharp, bright-green crystals with mustard-yellow ferrilotharmeyerite were found on 44 Level. (See also notes on adamite and olivenite.)

Paragenetic and General Notes

Zincolivenite is a relatively new species name (Chukanov et al., 2007) describing intermediate members of the adamite-olivenite solid solution series, i.e. those members with a Zn:Cu ratio of between 75:25 and 25:75. For practical purposes, many intermediates that have hitherto been known by the informal (and now discredited) name "cuproadamite", would fall within this approved definition of zincolivenite.

Some of Tsumeb's very rare and extremely rare arsenates occur in association with zincolivenite / "cuproadamite". The list of associated minerals provided is generic for the adamite-zincolivenite-olivenite series.

Minerals of the adamite-olivenite series (including zincolivenite) were considered by Keller (1977) to belong to "Type II" parageneses (i.e. mineral sequences forming at lower pH ranges). Zinc-rich members of the adamite-olivenite series were reported to have a wider range of associated secondary minerals than copper-rich members (Keller, op.cit.). Keller noted the following parageneses:

(1) quartz >> mottramite >> olivenite >> duftite >> malachite >> azurite >> malachite (ps. azurite)

(2) primary sulphides >> conichalcite >> adamite >> schultenite (or chudobaite)

(3) primary sulphides >> conichalcite >> adamite >> azurite >> malachite

(4) primary sulphides >> conichalcite >> tsumcorite >> adamite >> smithsonite.