Cerussite

minerals

phosgenite

caledonite

leadhillite

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Formula: Pb(CO3)
Carbonate, lead mineral
Specific gravity: 6.4 - 6.6
Hardness: 3 to 3½
Streak: White
Colour: Colourless, white, grey, yellow, brown, blackish (from inclusions of galena)
Solubility: Slightly soluble in hydrochloric acid and sulphuric acid; moderately soluble in nitric acid
Environments:

Carbonatites
Hydrothermal environments

Cerussite is generally a secondary mineral that occurs in the oxidation zone of high temperature lead-zinc deposits. It also occurs as alteration pseudomorphs after anglesite, phosgenite, leadhillite, caledonite, hydrocerussite, bournonite, linarite, pyromorphite and vanadinite. and also as pseudomorphs after calcite and sphalerite.

Lead will generally precipitate as primary galena from ore fluids rich in sulphur and lead. Removal of sulphur by precipitation of sulphides, however, may lead ultimately to an ore fluid from which galena cannot be precipitated, even with a high concentration of lead in solution. In these circumstances, cerussite, as well as pyromorphite and anglesite, could be precipitated as a primary mineral (Strens (1963), MM 33:722-3).

Anglesite and cerussite do not usually occur together. Generally anglesite is stable in lower pH (more acid) environments and cerussite in higher pH (more alkaline) environments. Seawater has a pH of approximately 8.3 (somewhat alkaline) so cerussite is the stable lead supergene mineral in contact with seawater (JRS 18.9,11).
For carbonate concentration slightly lower than atmospheric, cerussite and hydrocerussite can co-exist in alkaline environments, with leadhillite in more acid environments, and anglesite in yet more acid environments. For lower carbonate concentrations hydrocerussite completely replaces cerussite (JRS 18.11).

Localities

At the Chah Mileh mine, Iran, a cerussite - mimetite - hemimorphite pseudomorph after descloizite has been found (KL p173).

At Tsumeb, Namibia, cerussite pseudomorphs after anglesite, and mimetite pseudomorphs after cerussite, have been found (KL p172, 205).

At Berg Aukas, Grootfontein, Otjozondjupa Region, Namibia, cerussite occurs as a secondary mineral in the galena fraction of the ore bodies, associated with willemite, smithsonite and, rarely, quartz and goethite (R&M 96.2.123-124).

At the Whitwell quarry, Derbyshire, England, UK, cerussite occurs on a baryte - galena matrix (RES p137). Pyromorphite pseudomorphs after cerussite have been found here (KL p204).

At Croft quarry, Leicestershire, England, UK, cerussite has been found on galena crystals associated with analcime (JRS 20.13).

At the Snailbeach mine, near Minsterley, Shropshire, England, UK, cerussite occurs on quartz (RES p276).

At the Judkins quarry, Nuneaton, Warwickshire, England, UK, cerussite occurs with galena and calcite (RES p323).

At the Potter-Cramer property, Maricopa County, Arizona, USA, cerussite occurs as colourless crystals that fluoresce bright yellow under LWUV. Associated minerals include wickenburgite, willemite and fluorite. The wickenburgite is usually colourless, and fluoresces pink to red (R&M 96.1.29).

At the Flux mine, Santa Cruz county, Arizona, USA, pseudomorphs of cerussite after anglesite have been found (R&M 94.2.123).

At Cookes Peak mining district, Luna county, New Mexico, USA, cerussite was the dominant ore, produced as an oxidation product of galena (R&M 94.3.226).

At the Kabwe mine, Central Province, Zambia, cerussite occurs almost invariably encrusted with hemimorphite, and sometimes with tarbuttite (R&M 94.2.123).

Alteration

In the oxidation zone of epithermal veins primary galena PbS alters to secondary cerussite PbCO3 or anglesite depending on the acidity. Cerussite forms in more basic (alkaline) environments than anglesite (AM 100:1584-1594).

Formation of cerussite
galena may dissolve in carbonic acid from percolating rainwater to form lead ions, Pb2+.
PbS + 2H2CO3 → Pb2+ + H2S + 2HCO3>-
(KB).
These lead ions may then combine with carbonate ions CO32- to form cerussite, which is virtually insoluble in water and weak acids.
Pb2+ + CO32- → PbCO3

cerussite and aqueous H2AsO4-, Cl- and H+ to mimetite and aqueous H2CO3
5PbCO3 + 3H2AsO4- + Cl- + 7H+ ⇌ Pb5(AsO4)3Cl + 5H2CO3
or
5PbCO3 + 3HAsO42- + Cl- + 4H+ ⇌ Pb5(AsO4)3Cl + 5H2CO3
cerussite and mimetite can co-exist only under basic conditions at rather high PCO2 (MM 53.363-371).

duftite (s) and H2CO3 (aq) to cerussite (s), malachite (s), H2AsO4- (aq) and H+ (aq)
2PbCuAsO4(OH) + 3H2CO3 ⇌ 2PbCO3 + Cu2CO3(OH)2 + 2H2AsO4- + 2H+
(MM 52.688)

litharge + water + calcite = cerussite + Ca2+ + (OH)-
PbO + H2O + CaCO3 = PbCO3 + Ca2+ + 2OH-
(JRS 15.25-26)

Stability

The Activity-pH diagram below was calculated for some lead minerals. Boundaries are calculated for constant activity (roughly equivalent to concentration) of (SO4)2- and constant partial pressure (also roughly equivalent to concentration) of CO2, over a range of values of pH and of Cl1- activity. In this case the concentration of CO2 is appreciably more than the atmospheric value.
For seawater aCl- = 10-0.5 and pH = 8.2, so here cerussite is the stable mineral in contact with seawater.
Cerussite is stable in an alkaline or slightly acid environment and a wide range of Cl- ions. If the concentration of CO2 decreases the stability field of cerussite narrows to become more alkaline (higher pH) then disappears in favour of hydrocerussite (JRS 15.18-23).

stability Pb.jpg

The lead mineral formulae are:
cotunnite PbCl2
phosgenite Pb2(CO3)Cl2
cerussite Pb(CO3)
anglesite Pb(SO4)













The Activity-pH diagram below is similar, but in this case the concentration of CO2 is less than the atmospheric value.
Hydrocerussite and cerussite can co-exist at this level of CO2 concentration. At higher concentrations cerussite is the stable mineral, and at lower concentrations Hydrocerussite is the stable mineral (JRS 15.21).

stability Pb 4.jpg

The lead mineral formulae are:
cotunnite PbCl2
paralaurionite PbCl(OH)
mendipite Pb3O2Cl2
cerussite Pb(CO3)
hydrocerussite Pb3(CO3)2(OH)2
anglesite Pb(SO4)
leadhillite Pb4(CO3)2(OH)2













The diagram below is similar, but in this case the concentration of CO2 is less than the atmospheric value.
Hydrocerussite and cerussite can co-exist at this level of CO2 concentrations. At higher concentrations cerussite is the stable mineral, and at lower concentrations hydrocerussite is the stable mineral (JRS 15.21).

stability Pb 4.jpg

The lead mineral formulae are:
cotunnite PbCl2
paralaurionite PbCl(OH)
mendipite Pb3O2Cl2
cerussite Pb(CO3)
hydrocerussite Pb3(CO3)2(OH)2
anglesite Pb(SO4)
leadhillite Pb4(CO3)2(OH)2











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