The deposit has produced an attractive suite of colorful, well-crystallized, hydrous sulfates including coquimbite, halotrichite, krausite, metavoltine, potassium alum, quenstedtite, r^merite and voltaite
. Associated minerals include botryogen, copiapite, anhydrite, gypsum, melanterite, marcasite and sulfur.
Several blue and orange-colored sulfates have not been positively identified but probably include romerite, voltaite
, metavoltine and chalcanthite.
Also in his stock were colorful (but unfortunately unstable) fine crystals of the iron sulfates voltaite
, coquimbite and botryogen.
, metavoltine, melanterite, copiapite and halotrichite, have been found at outcrops of pyritic Chattanooga Shale in Kentucky and at roadcuts exposing pyritic coal beds in Kentucky, Tennessee, and Pennsylvania (e.g., Coskren, 1981).
Among them were colorful (but unfortunately unstable) iron sulfates such as voltaite
, coquimbite, botryogen and others from the abandoned subterranean workings in the area of the Alfred pit, Riotinto mine, Riotinto, Huelva.
Ahlfeld and Reyes (1955) report silky orange sideronatrite associated with voltaite in the ancient workings.
Lindgren and Creveling (1928) reported waxy, olive-green voltaite crystals associated with orange sideronatrite in the ancient workings.
occurs as complex cuboctahedra and dodecahedra, dark oil-green to black-green in color and 0.25 mm across (D.
Fine native copper, large barite crystals, gratonite crystals, spectacular formations of post-mining sulfates, and the world's finest voltaite are among the features of this historic deposit.
The finest voltaites in the world are probably those from levels 29 and 33 in the Pozo Alfredo workings.
Scattered, pale orange crystals of vitreous, translucent romerite have been found at the Plaka mine, associated with halotrichite, chalcanthite and voltaite