Mineral Species
Talc
Type Locality
No
Composition
Mg3Si4O10(OH)2
Crystal System
Triclinic
Status at Tsumeb
Questionable
Entry Number
Species; TSNB341
General Notes
Söhnge (1964) noted the presence of talc coatings on fragments in the "… shear breccia of the ore pipe" between 28 and 30 levels and suggested that it was genetically related to local shearing (rather than hydrothermal metamorphism). Söhnge (1964) also noted the presence of talc in mineralised shears below 30 Level and described "talc alteration" of the "pseudo-aplite" (= felspathic sandstone).
It appears that the mention of talc in these papers (Söhnge 1964) provided the rationale for the inclusion of talc in subsequent listings of mineral species from Tsumeb including Pinch and Wilson (1977), Keller (1984), Lombaard et al. (1986), Gebhard (1991, 1999), Von Bezing et al. (2016) and www.mindat.org (accessed August 2022). Interestingly, none of these authors elaborated on the mode of occurrence of talc, although Lombaard et al. (1986) considered it to be a "common" mineral.
According to Hughes (1987) the supposed "talc alteration" of the feldpathic samdstone described by Söhnge (1964) was later shown to be "illite", while XRD studies of material from supposed "talc shears" showed a mixture of "…illite, quartz, minor kaolinite, but no talc."
It is possible, therefore, that the talc occurrences described by Söhnge (1964) were incorrectly identified and, for this reason, the occurrence of talc at Tsumeb is considered questionable.
Associated Minerals
biotite series (?)
