Mimetite

TSNB835
Specimen
Klein, W.
Exhibit 1. Mimetite; 95 mm.
Exhibit 1. Mimetite; 95 mm.
Image Credit: Malcolm Southwood photo; courtesy of the NHM London
Exhibit 2. Mimetite; 95 mm.
Exhibit 2. Mimetite; 95 mm.
Image Credit: Malcolm Southwood photo; courtesy of the NHM London
Exhibit 3. 50 mm field of view.
Exhibit 3. 50 mm field of view.
Image Credit: Malcolm Southwood photo; courtesy of the NHM London
Exhibit 4. 32 mm field of view.
Exhibit 4. 32 mm field of view.
Image Credit: Malcolm Southwood photo; courtesy of the NHM London
Exhibit 5. Specimen label (NHM London).
Exhibit 5. Specimen label (NHM London).
Image Credit: Malcolm Southwood photo; courtesy of the NHM London
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Specimen Title

Mimetite

Associated Minerals

hematite (?); smithsonite (?)

Principal Mineral

Mimetite

Size

Cabinet; 95mm

Location in the Mine

First oxidation zone

Provenance

Klein, W.

Collection

NHM London; BM.1929,1856

Entry Number

Specimen; TSNB835

Associated Minerals

hematite (?); smithsonite (?)

Description

Stout, composite, prismatic crystals of mimetite, closely intergrown and with unusual skeletal terminations, possibly due to etching (?). A note with the specimen states that infrared spectroscopy (analysis IR # 957) has demonstrated "v. slight" substitution of phosphate (for arsenate).


The NHM London label (Exhibit 5) describes the specimen as "Group of brown mimetite prisms encrusted with smithsonite", but it appears to consist almost entirely of mimetite. The orange-brown colour may, however, be due to the presence of microscopic hematite (?) inclusions.


The specimen was gifted to Mr L. J. Spencer (curator of the British Museum) by Wilhelm Klein, production manager at Tsumeb, during Spencer’s 1929 visit to Tsumeb. This dates it unequivocally to the first oxidation zone.