Tsumcorite (on mimetite)

TSNB832
Specimen
Maucher, W.
Exhibit 1. Tsumcorite (on mimetite); 90 mm.
Exhibit 1. Tsumcorite (on mimetite); 90 mm.
Image Credit: Malcolm Southwood; courtesy of the NHM London
Exhibit 2. 25 mm field of view.
Exhibit 2. 25 mm field of view.
Image Credit: Malcolm Southwood; courtesy of the NHM London
Exhibit 3. 25 mm field of view.
Exhibit 3. 25 mm field of view.
Image Credit: Malcolm Southwood; courtesy of the NHM London
Exhibit 4. 20 mm field of view.
Exhibit 4. 20 mm field of view.
Image Credit: Malcolm Southwood; courtesy of the NHM London
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Specimen Title

Tsumcorite (on mimetite)

Associated Minerals

malachite; mimetite

Principal Mineral

Tsumcorite

Size

Cabinet; 90mm

Location in the Mine

First oxidation zone

Provenance

Maucher, W.

Collection

NHM London; BM.1925,93

Entry Number

Specimen; TSNB832

Associated Minerals

malachite; mimetite

Description

A mesh of intergrown prismatic mimetite crystals (exceptionally to 8 mm), lemon-yellow and highly translucent, resting on a shard of sulphide ore. The mimetite is partly overgrown by well-formed sub-mm crystals of orange-brown tsumcorite. A little micro-botryoidal malachite completes the paragenesis.



The specimen was acquired from Wilhelm Maucher (of Munich) in 1929, erroneously identified as "sideronatrite". Its vintage dates it unequivocally to the first oxidation zone.



Some 35 years later, in 1964, an unknown mineral was discovered in the second oxidation zone and subsequently described by Geier et al. (1971) as tsumcorite. Peter Embrey (then curator at the NHM London) recognised the similarity of this specimen and provided material and a microprobe analysis which contributed to the tsumcorite description (Geier et al. 1971; p.307). Interestingly, there is no registered type specimen for tsumcorite, but BM.1925,93 can arguably be considered co-type material.