Annabergite

Crystal System: Monoclinic
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Nickel arsenate hydrate
Chemical Formula: Ni3(AsO4)2.8H2O
Method(s) of Verification: not known.

Chemical Group:

  • Arsenates

Geological Context:

  • Supergene: post-mining oxidation & weathering deposits
Introduction: annabergite is a supergene alteration product which forms during the weathering of primary Ni- and As-bearing minerals. As such, it is generally found in the oxidized zones of polymetallic hydrothermal mineral veins. Associated species include other arsenate minerals and particularly the cobalt arsenate, erythrite.
Occurrence in Wales: only one very limited occurrence of annabergite has to date been reported from Wales, despite the wide distribution of nickel-bearing primary minerals. However, the specific combination of primary Ni and As minerals is extremely rare in Wales: Ni-S and Ni-Sb are the chief associations.

Key Localities:

  • Great Orme Copper Mines, Llandudno, Gwynedd: annabergite forms microscopic coatings on gersdorffite occurring on fractures in hydrocarbon or "mineral pitch" (P. Eakin, unpublished data).

References:

There are no references for this specimen.