lammerite

Lammerite was found in the North-East Stope of 35 Level, in early 1980 by TCL mineralogist John Innes. Innes reported his find to Paul Keller who published a note on the discovery (Keller 1981).

Keller (1981) described "… very beautiful … idiomorphic crystals" of lammerite forming "… radiating groups of dark green, fused individual crystals to 2 mm which, superficially resemble olivenite or brochantite".

Keller (1981) and Keller and Bartelke (1982) described an unusual paragenesis in which lammerite is associated with anhydrite, chalcanthite, leightonite, "a TK-like mineral" and "unidentified silicates".

The "TK-like mineral" was later found to be an iron-bearing thometzekite (Gebhard 1999).

The sprays of lammerite were "buried" under a crust of chalcanthite and the late Bill Pinch recalled working on a specimen for three days with an eyedropper of water to gently remove the chalcanthite to expose lammerite (Bill Pinch, pers. comm. to M. Southwood, February 2013).

Keller (1981) discussed the conditions under which these minerals might have formed and hypothesised that they crystallised at higher temperatures than most of the secondary minerals at Tsumeb.

Keller and Bartelke (1982) proposed the following paragenesis (modified from Keller 1981):

Lammerite is also recorded from 44 Level in the third oxidation zone where occurs in the type assemblage for erikapohlite. Here it presents as lamellar microcrystals in association with conichalcite, erikapohlite and an unknown Zn-Fe-Cu-(Mg-Ca) arsenate in granular quartz associated with tennantite ore (Schlüter et al. 2013).

anhydrite; chalcanthite; conichalcite; erikapohlite; leightonite; quartz; tennantite-(Zn); thometzekite