Abundant. Occurs in all three oxidation zones, but especially common in the upper levels of the mine (first oxidation zone).
- 1st Oxidation Zone
- 2nd Oxidation Zone
- 3rd Oxidation Zone
Crystals of non-pseudomorphous malachite to 10 mm were found in the first oxidation zone, as were very fine examples of malachite pseudomorphs after azurite. In the second oxidation zone, the so-called "Perkins Sams" azurite pocket also yielded very large and attractive malachite pseudomorphs. Large crystals of non-pseudomorphous malachite (with cuprite) were again found in the third oxidation zone (Gebhard, 1999).
Paragenetic and General Notes
Malachite is the most common secondary copper mineral at Tsumeb (Bartelke, 1976; Keller, 1977). Small acicular crystals of malachite, and aggregates thereof, are commonly associated with many other species.
A high proportion of the malachite specimen material from Tsumeb is pseudomorphous after azurite.
Malachite formed at several stages of the supergene process and is a constituent of a large number of diverse associations. It is generally an important component of Keller's (1977) "Type I" paragenesis (i.e. mineral sequences formed at higher pH ranges). Keller noted the following parageneses:
(1) duftite >> dundasite >> cerussite >> azurite >> malachite (ps. azurite).
(2) quartz >> mottramite >> olivenite >> duftite >> malachite >> azurite >> malachite (ps. azurite).
Malachite also occurs in the following Type II (i.e. lower pH) sequences:
(3) primary sulphides >> brochantite >> (posnjakite + malachite) >> linarite >> serpierite.
(4) primary sulphides >> conichalcite >> adamite >> azurite >> malachite
Malachite has been reported to form pseudomorphs after the following minerals: aragonite (rare); azurite (abundant); copper (common); cuprite (common); enargite (rare); tennantite (rare); wulfenite (rare).
The following minerals have been reported to form pseudomorphs after malachite: rosasite (common, the so-called "double pseudomorph", with the malachite itself pseudomorphous after azurite).