johillerite

Johillerite was discovered in cavities in heavily oxidised tennantite-chalcocite ore. The exact location in the mine was not recorded, but Keller et al. (1982a) note that the paragenesis is consistent with the East 9 Pillar on 31 Level in the second oxidation zone. Johillerite, IMA 1980-014, was named for Dr Johannes-Erich Hiller (1911-1972), professor of mineralogy at Stuttgart University, Germany (Keller et al. 1982a). The holotype specimen of johillerite is conserved at the Institut für Mineralogie und Kristallchemie, Universität Stuttgart, in Germany (Prof. Paul Keller Collection; catalogue number TM-80.14-Tr) and co-type material is held by the Smithsonian Institution in Washington D.C. (catalogue number 146969).

On the type specimen, presumed to be from 31 Level, johillerite occurs as radiating masses of blades and fibres (to 2 mm) elongated on [001]. It is associated with earlier conichalcite and zincolivenite and the colour is a startling violet-blue. Johillerite appears to be the youngest mineral in the sequence, with the following paragenesis proposed by Keller et al. (1982a):

sulphide ore >> conichalcite >> cuprian adamite [=zincolivenite] >> johillerite

Keller and Bartelke (1982) include johillerite as part of their proposed paragenesis for the rare mineral assemblage from the East 9 Pillar on 31 Level. The paragenesis, believed to have formed under acid conditions, comprises conichalcite and zincolivenite (most abundant) and an extensive suite of rare minerals including austinite, claudetite, gaitite, helmutwinklerite, keyite, koritnigite, leiteite, ludlockite, o’danielite, prosperite, schultenite, stranskiite and warikahnite. A proposed sequence of crystallisation is mapped by Keller and Bartelke (1982; page 145 – Table 1).

In the third oxidation zone johillerite occurs with leiteite and zincolivenite (Gebhard, 1999) and was part of the so-called "Zinc Pocket" paragenesis on 44 Level. A specimen from this occurrence in the Southwood Collection (MS 2018.081) comprises inclusions of blue johillerite and ianbruceite (both EMPA confirmed) and brownish-orange warikahnite in leiteite.

austinite; chalcocite; claudetite (?); conichalcite; gaitite; helmutwinklerite; hörnesite; ianbruceite; keyite; koritnigite; köttigite; legrandite; leiteite; ludlockite; o’danielite; prosperite; schultenite; stranskiite; tennantite-(Zn); warikahnite; zincolivenite