ISSN:
1572-901X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary Free energies of formation of the rare copper(II) secondary minerals linarite, (Pb,Cu)2SO4(OH)2, caledonite, Pb5Cu2CO3(SO4)3(OH)6, and wherryite, Pb4CuCO3(SO4)2O(OH,Cl)2, and of the complex lead(II) species leadhillite, Pb4SO4(CO3)2(OH)2, have been estimated using solution techniques. Values derived are: −1212(1), −4328(2), −2871(1), and −2525(4) kJ mol−1 at 298.2K respectively, and have been used to construct stability field diagrams involving these, and related species. They are anomalous in the sense that they are not the usually found sulphates and carbonates of copper(II) and lead(II) in the natural environment. The data, together with field observations of mineral associations, has been used to reconstruct part of the chemical paragenetic sequence of the oxidized zone of the Mammoth —St. Anthony Mine, Tiger, Arizona, U.S.A. Many of the rare species above and other complex halides of copper(II), silver(I) and lead(II) formed under conditions where $$a_{H_2 CO_3^0 } $$ and aSO 4 2− were comparatively low, and around neutral values of pH. Several trends in the chemistry of the development of the anomalous oxidized zone at Tiger are apparent, and these are discussed in the light of the above findings.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00623805
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