Mode of formation of some rare copper(II) and lead(II) minerals from aqueous solution, with particular reference to deposits at tiger, Arizona

Abdul-Samad, Fawzy A.; Thomas, J. H.; Williams, Peter A.; Bideaux, Richard A.; Symes, R. F.

doi:10.1007/bf00623805

Cited by 17 publications

(23 citation statements)

References 6 publications

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“…In the 'exclusively lead ores' Temple (1956) notes leadhillite after cerussite, followed by lanarkite, but less commonly than the classic order galena, PbS ~ anglesite ~ cerussite. A further observation of hydrocerussite after cerussite firmly establishes that during the formation of the secondary minerals, the an,co o fell and then rose again, parallelling observations concerning the emplacement of the complex oxide zone at Tiger, Arizona (Abdul-Samad et al, 1982). All these observations neatly fit the experimental results on the thermodynamic stability of lanarkite, and thus its rarity.…”

supporting

confidence: 77%

“…

W E have recently reported (Humphreys et al, 1980;Abdul-Samad et al, 1982) the free energies of formation of a variety of chloride-bearing minerals of Pb(II) and Cu(II) together with carbonate and sulphate species of the same metals including leadhillite, Pb,SO4(COa)2(OH)2, caledonite, PbsCu2CO3(SO4)3(OH)6, and linarite, (Pb,Cu)2 SO4(OH)2. By using suitable phase diagrams it has proved possible to reconstruct, in part, the chemical history of the development of some complex secondary mineral assemblages such as those at the Mammoth-St. Anthony mine, Tiger, Arizona, and the halide and carbonate suite of the Mendip Hills, Somerset.

A celebrated locality for the three sulphatebearing minerals above is the Leadhills-Wanlockhead district of Scotland (Wilson, 1921; Heddle, I923, 1924) from which the minerals leadhillite and caledonite were first described, and in which several other rare species have been noted including susannite, the hexagonal dimorph of leadhillite, hydrocerussite, Pba(CO3)2(OH)2 and lanarkite, Pb2OSO ,.

…”

mentioning

confidence: 99%

“…W E have recently reported (Humphreys et al, 1980;Abdul-Samad et al, 1982) the free energies of formation of a variety of chloride-bearing minerals of Pb(II) and Cu(II) together with carbonate and sulphate species of the same metals including leadhillite, Pb,SO4(COa)2(OH)2, caledonite, PbsCu2CO3(SO4)3(OH)6, and linarite, (Pb,Cu)2 SO4(OH)2. By using suitable phase diagrams it has proved possible to reconstruct, in part, the chemical history of the development of some complex secondary mineral assemblages such as those at the Mammoth-St. Anthony mine, Tiger, Arizona, and the halide and carbonate suite of the Mendip Hills, Somerset.…”

mentioning

confidence: 99%

“…Inspection of equations (4)- (9) indicates that lanarkite is thermodynamically stable only at very low activio ties of H2COa(aq). It is clear from other studies involving secondary copper and lead minerals (Abdul-Samad et al, 1982) that such low activities are achieved only rarely in nature and hence lanarkite should be an uncommon mineral.…”

mentioning

confidence: 99%

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Chemistry of formation of lanarkite, Pb₂OSO₄

Abdul-Samad¹,

Thomas²,

Williams³

et al. 1982

Mineral. mag.

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W E have recently reported (Humphreys et al., 1980;Abdul-Samad et al., 1982) the free energies of formation of a variety of chloride-bearing minerals of Pb(II) and Cu(II) together with carbonate and sulphate species of the same metals including leadhillite, Pb,SO4(COa)2(OH)2, caledonite, PbsCu2CO3(SO4)3(OH)6, and linarite, (Pb,Cu)2 SO4(OH)2. By using suitable phase diagrams it has proved possible to reconstruct, in part, the chemical history of the development of some complex secondary mineral assemblages such as those at the Mammoth-St. Anthony mine, Tiger, Arizona, and the halide and carbonate suite of the Mendip Hills, Somerset.A celebrated locality for the three sulphatebearing minerals above is the Leadhills-Wanlockhead district of Scotland (Wilson, 1921; Heddle, I923, 1924) from which the minerals leadhillite and caledonite were first described, and in which several other rare species have been noted including susannite, the hexagonal dimorph of leadhillite, hydrocerussite, Pba(CO3)2(OH)2 and lanarkite, Pb2OSO ,. Preliminary attempts to incorporate this last species into our thermodynamic model for secondary mineral formation were frustrated because of the wide variation in the reported values for its free energy of formation. We have therefore redetermined this quantity, and use it to outline possible conditions for the crystallization oflanarkite from aqueous solution.

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supporting

confidence: 77%

“…

…”

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Chemistry of formation of lanarkite, Pb₂OSO₄

Abdul-Samad¹,

Thomas²,

Williams³

et al. 1982

Mineral. mag.

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“…Phosgenite and Samad et al, 1982). In most cases, a subsequent phosgenite cerussite transformation can be observed.…”

Section: Ntroductionmentioning

confidence: 99%

In situ atomic force microscope observations of a dissolution–crystallisation reaction: the phosgenite–cerussite transformation

Pina

Fernández-Dı́az

Prieto

et al. 2000

Geochimica et Cosmochimica Acta

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Abstract-The dissolution-reprecipitation reaction of phosgenite (Pb2CI2C03) to cerussite (PbC03) has been observed in situ in a fluid cell of an atomic force microscope (AFM). The (00 I) face of phosgenite, in contact with static carbonated aqueous solutions, rapidly begins to dissolve. AFM observations show that dissolution occurs by generation and spread of square-shaped etch pits with sides parallel to (I 10) directions. The dissolution of the (110) steps is isotropic and the etch pits therefore remain square shaped during the dissolution process, as dictated by the existence of a fourfold axis perpendicular to the phosgenite (00 I) face. Two types of (110) etch pits were found: short-lived shallow pits, of one unit cell depth (8.8 A), and deep pits, which rapidly reach depths between 10 and 60 nrn. A few minutes after the dissolution begins, only the deep pits remain and subsequent dissolution of the phosgenite (001) surface proceeds by increasing their width and depth. The increase of Pb 2 + and CO�-concentration in the aqueous solution as a consequence of the dissolution sharply increases the supersaturation for PbC03. As a result, after a certain incubation time, cerussite crystals nucleate on the phosgenite (001) surface and a coupled process of dissolution-crystallisation starts. Cerussite crystals, which grow by a spiral-growth mechanism, distort the concentration field around them. As a consequence, phosgenite dissolution is accelerated in the proximity of such growing cerussite individuals and both the fonnation of new deep etch pits and the development of irregular dissolution fronts are observed. Further phosgenite dissolution leads to an increase of cerussite nucleation and growth rates, in such a way that this dissolution-crystallisation phenomenon can be considered as an autocatalytic process.

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