The supergene processes operating here were not as intense as in the other mines, and sometimes lenses of unaltered tennantite, rimmed by chenevixite and other arsenic minerals, remain.
Chenevixite [Cu.sup.2+.sub.2][Fe.sup.3+.sub.2] [(As[O.sub.4]).sub.2][(OH).sub.4]*[H.sub.2]O
At the La Atalya prospect chenevixite is a direct product of tennantite oxidation, forming as crusts and disseminated areas of alteration in tennantite (see Table 4).
At the Umbria de Ramonete prospect, chenevixite forms yellow-green to grass-green crusts and masses with olivenite, and powdery to nodular precipitates on quartz.
In the goethite cavities, olivenite is found together with cornwallite and conichalcite; in the quartz cavities, it can be accompanied by phannacosiderite, lavendulan and chenevixite. Olivenite has also been found in a few specimens on scorodite-mansfieldite and yukonite.
(1996), small crystals of pharmacolite were found in the Umbria de Ramonete prospect, associated with chenevixite, but analytical data have not been provided, and the presence of pharmacolite seems very doubtful.
A similar process is observed in La Atalaya, where chenevixite, tyrolite, cornwallite, olivenite and azurite were the first-formed secondary minerals, partially replaced thereafter by conichalcite.