Image Credit: Malcolm Southwood
Image Credit: Malcolm Southwood
Image Credit: Malcolm Southwood
Specimen Title
malachite after cuprite (w. mimetite and wulfenite)
Associated Minerals
duftite; goethite; mimetite; quartz; wulfenite
Principal Mineral
Precursor Mineral
Size
Cabinet; 96mm
Provenance
(not assigned)
Collection
MGMH; 108879
Entry Number
Specimen; TSNB728
Description
Encrustation pseudomorphs of malachite after cuprite crystals (to 1.5 mm); the malachite surfaces are botryoidal (under magnification; Exhibit 2), but the octahedral or cubo-octahedral habit of the cuprite remains discernible in many cases. Some broken structures reveal that the cuprite has been encrusted rather than replaced. Sparse aggregates of cream-coloured mimetite (exceptionally to 12 mm) are also present. Both the pseudomorphs and the mimetite rest on goethite. The reverse of the specimen shows a matrix of quartz, with greyish-green duftite (EDS verified; Frank Keutsch, Harvard University 2025; Exhibit 3) with intergrown tabular crystals of wulfenite (exceptionally to 3 mm but typically sub-mm). The smaller wulfenite crystals appear colourless and transparent; the larger crystals are weakly toffee-coloured.
The specimen was acquired by MGMH in 1997 but neither its source nor its location in the mine are recorded.
