arsentsumebite after mimetite (w. malachite)

TSNB734
Specimen
Klein, W.
Exhibit 1. Arsentsumebite after mimetite (w. malachite); 49 mm.
Exhibit 1. Arsentsumebite after mimetite (w. malachite); 49 mm.
Image Credit: Malcolm Southwood
Exhibit 2. Arsentsumebite after mimetite (w. malachite); 49 mm.
Exhibit 2. Arsentsumebite after mimetite (w. malachite); 49 mm.
Image Credit: Malcolm Southwood
Exhibit 3. 25 mm field of view.
Exhibit 3. 25 mm field of view.
Image Credit: Malcolm Southwood
Exhibit 4. 22 mm field of view.
Exhibit 4. 22 mm field of view.
Image Credit: Malcolm Southwood
Thumbnail by 1Thumbnail by 2Thumbnail by 3Thumbnail by 4

Specimen Title

arsentsumebite after mimetite (w. malachite)

Associated Minerals

cerussite; malachite; mimetite

Principal Mineral

Arsentsumebite

Precursor Mineral

Mimetite

Size

Miniature; 49mm

Location in the Mine

First oxidation zone; 4 Level

Provenance

Klein, W.

Collection

MGMH; 110889

Entry Number

Specimen; TSNB734

Description

Spherical sprays (to 20 mm) of acicular malachite rest on encrustation pseudomorphs of arsentsumebite (SEM/EDS confirmed; Martin Števko; Slovak Academy of Sciences, Bratislava, Slovakia) after slender prismatic mimetite crystals (to 45 mm; exhibits 1 and 2). Broken surfaces of the pseudomorphs reveal fresh mimetite and demonstrate that the replacement – or encrustation (?) – is less than 0.5 mm thick (exhibits 3 and 4).


Aggregates (to 4 mm) of colourless to very pale yellow second generation (?) mimetite crystals have formed locally on the arsentsumebite (exhibits 3 and 4). A single colourless cerussite crystal (circa 0.5 mm) completes the paragenesis, also resting on arsentsumebite.


The specimen was number 976 in the collection of Wilhelm Klein, production manager at Tsumeb between 1916 and 1939. His catalogue records that the specimen is from 4 Level in the first oxidation zone.