Willemite (on dolomite and smithsonite)

TSNB495
Specimen
Bruce, I.Smith, A.G.Smith, A.G.
Exhibit 1. Willemite (on dolomite and smithsonite); 53 mm.
Exhibit 1. Willemite (on dolomite and smithsonite); 53 mm.
Image Credit: Malcolm Southwood
Exhibit 2. 11 mm field of view.
Exhibit 2. 11 mm field of view.
Image Credit: Malcolm Southwood
Exhibit 3. XRD verification of dolomite and smithsonite by Paul Carr, University of Wollongong, Australia; October 2024
Exhibit 3. XRD verification of dolomite and smithsonite by Paul Carr, University of Wollongong, Australia; October 2024
Image Credit: Malcolm Southwood
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Specimen Title

Willemite (on dolomite and smithsonite)

Associated Minerals

dolomite; rosasite (?); smithsonite

Principal Mineral

Willemite

Size

Cabinet; 53mm

Location in the Mine

Undetermined

Provenance

Smith, A.G.

Collection

Geoscience Australia; R38175

Entry Number

Specimen; TSNB495

Associated Minerals

dolomite; rosasite (?); smithsonite

Description

A matrix of iron-stained dolostone hosts a vug lined with an intergrown mixture of dolomite and smithsonite; both are white and visually indistinguishable, but both are XRD-confirmed (Exhibit 3). The surface of the dolomite / smithsonite is decorated with bright, apple-green willemite crystals (to 3 mm) which have formed preferentially over fractures in the underlying carbonate (Exhibit 2). The colour of the willemite is unusual for Tsumeb. Note also the twinned willemite crystal at upper left of the close-up image and sparse, tiny spherules of a blue-green mineral - possibly rosasite (?) (Exhibit 2).

The specimen is from the collection of A. Glen Smith, which was donated to National Museum of Australia in 1982; it is now housed at Geoscience Australia, in Canberra.

The location in the mine is not recorded.