ojuelaite

TSNB257

Species

Ojuelaite: A spherical spray (circa 0.8 mm) of acicular ojuelaite crystals (XRD verified) associated with arseniosiderite (buff), schneiderhöhnite (black, platy) and scorodite (blue). 25 mm field of view.
Ojuelaite: A spherical spray (circa 0.8 mm) of acicular ojuelaite crystals (XRD verified) associated with arseniosiderite (buff), schneiderhöhnite (black, platy) and scorodite (blue). 25 mm field of view.
Image Credit: Stephen Rust

Title

ojuelaite

Composition

ZnFe3+2(AsO4)2(OH)2·4H2O

Crystal System

Monoclinic

Status at Tsumeb

Confirmed

Abundance

Extremely rare

Distribution

Second oxidation zone.

Paragenesis

Supergene.

Type Locality

No

Entry Type

Species TSNB257

General Notes

Ojuelaite occurs as bundles (to 2 mm) or radiating sprays (c. 1 mm) of fibrous, silky, yellow to olive-green crystals in small cavities associated with goethite and smithsonite (Keller and Bartelke 1982) or with hematite, scorodite, and schneiderhöhnite in partly oxidised tennantite-rich ore.

Keller and Innes (1986) noted an occurrence of ojuelaite from the West 40 Stope on 32 Level where they also found betpakdalite, paradamite and pharmacosiderite.

A specimen of ojuelaite from the Lammer Collection, obtained by Lammer in Tsumeb in 1984 and now in the Southwood Collection (MS2015.081), includes sprays and bundles of ojuelaite associated with scorodite, siderite, schneiderhöhnite, arseniosiderite and goethite in a vug in sulphide ore; partings in the sulphide also host minor leiteite and ludlockite.

A specimen in the Feinglos Collection at Harvard University (MGMH 2022.4.3911L) shows a completely different paragenesis in which ojuelaite is associated with smithsonite and conichalcite-duftite on a matrix rich in goethite and calcite.

Associated Minerals

arseniosiderite; betpakdalite-CaCa (?); calcite; conichalcite-duftite; goethite; hematite; leiteite; ludlockite; paradamite; pharmacosiderite; quartz; schneiderhöhnite; scorodite; siderite; smithsonite; tennantite-(Zn)