Zincrosasite

Strunz (1959) described a zinc-dominant variety of rosasite with a molar ratio of zinc to copper of 58.60:51.94. He proposed the name zincrosasite in allusion to its compositional relationship (Daltry 1992). Strunz’s description was superficial to say the least; he noted that the XRD spectrum differs significantly from malachite, but only marginally from rosasite and he provided a cursory account of habit, colour and hardness, describing zincrosasite as a very soft mineral, almost white in colour, with a tinge of light blue. He described the habit as radial aggregates formed of fibrous crystals. Strunz’s type material is conserved at the Institut für Mineralogie und Kristallographie, Technische Universität, Berlin (catalogue number N1377)

The IMA considers zincrosasite a species of questionable validity (http://cnmnc.units.it/; accessed January 2023).

Bartelke (1976) and Pinch and Wilson (1977) clearly treated zincrosasite as a variety of rosasite rather than a valid species. Even Strunz and Tennyson (1967) do not include zincrosasite in their contemporary list of Tsumeb’s type locality minerals.

It is therefore puzzling that Embrey and Fuller (1980) awarded it full species status.

In recent years the IMA has considered zincrosasite as a questionable species (http://cnmnc.units.it/ ; accessed January 2023). Fehér et al. (2015) explained that zincrosasite, as described by Strunz (1959), does not constitute a distinct mineral species because, while zinc is dominant in terms of total cations, one of the two cation sites in the structure remains copper-dominant, which is no different from the situation in rosasite.

Significantly, zincrosasite is omitted from the lists of Tsumeb minerals published by Keller (1984), Lombaard et al. (1986), Gebhard (1990) and Gebhard (1999). Daltry (1992), however, includes it in his inventory of valid Namibian type minerals.

Questionable status is retained for zincrosasite at Tsumeb pending a clear ruling from the IMA regarding its validity as a mineral species.

azurite (?); cerussite (?); hemimorphite (?)