Formula: Pb7Cu2(SO4)4(SiO4)2(OH)2
Compound sulphate
Specific gravity: 6.45
Colour: Light green, yellow or bright yellowish-green
Solubility: Slowly soluble in cold hydrochloric or nitric acid

Hydrothermal environments


At the type locality, the Mammoth-Saint Anthony Mine, St. Anthony deposit, Tiger, Mammoth Mining District, Pinal county, Arizona, USA, wherryite was found associated with chrysocolla, diaboleite and paralaurionite. In 1943 a mining engineer discovered a small vug of leadhillite crystals associated with cerussite, anglesite, phosgenite, paralaurionite, hydrocerussite, diaboleite, boleite, matlockite and quartz. Within the cavity was some friable chalcocite with a relict structure of the galena which it has replaced. The massive wall of the vug consisted of a light-green fine granular mineral enclosing some chrysocolla, and at the cavity some diaboleite and paralaurionite. This green matrix proved to be a the new mineral wherryite, described in 1950. At the Saint Anthony deposit the basement rock is a quartz monzonite, intruded by dikes of aplite and by bodies of andesite porphyry, now altered, as well as by later dikes and sills of rhyolite and intrusive breccias of the earlier rocks. Part of the paragenesis of the leadhillite vug may be interpreted as follows: A mass of primary galena, close to the water table, was partly replaced by chalcocite in the course of secondary enrichment of the copper. Advancing oxidation altered some of the galena to anglesite, which was gradually replaced by cerussite, while some of the chalcocite was altering to chrysocolla. The sequence, galena to anglesite to cerussite, is the normal course of the weathering process. At some stage of this normal sequence, however, a remarkable reversal took place with the formation of the complex sulphates leadhillite and wherryite, as well as the formation of the rare basic carbonate hydrocerussite, and the rare oxychlorides diaboleite and paralaurionite, and the chlorofluoride matlockite. It may be that this unusual paragenesis was caused by an influx of solutions containing chlorine ions. The wherryite has a fine granular texture and is usually intimately associated with leadhillite, paralaurionite and chrysocolla. (AM 35.93-98).

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