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 (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 Lingchuan Mine, Lingchuan County, Guilin, Guangxi, China, white, crystalline, translucent cerussite has been found on a limonite matrix (AESS).
Cerussite from the Lingchuan Mine - Image
At the Chah Milleh Mine, Chah Milleh, Anarak District, Nain County, Isfahan Province, Iran, a cerussite - mimetite - hemimorphite pseudomorph after descloizite has been found (KL p173).
Cerussite from Chah Milleh - Image
At the Nakhlak Mine, Anarak District, Nain County, Isfahan Province, Iran, epigenetic (formed later than the surrounding or underlying rock formation) vein deposits and metasomatic replacement bodies are hosted by a chalky Upper Cretaceous (100.5 to 66 million years ago) limestone. The limestone underwent dolomitisation prior to sulphide mineralisation. The principal primary ore mineral is galena, associated with minor or trace amounts of sphalerite, tetrahedrite -tennantite, pyrite and chalcopyrite as inclusions. The main secondary ore mineral is cerussite, sometimes associated with minor amounts of anglesite, plattnerite, wulfenite, minium, mimetite, covellite, chalcanthite, malachite and goethite. Many trace elements are present in the primary galena, but most notably it is rich in silver and antimony and poor in bismuth.
Cerussite occurs in beautiful, reticulated “snowflake” specimens. Vugs and cavities are abundant and rich in crystallised cerussite, ranging in colour from snow-white through cream to dark grey, sometimes with a dusting of orange mimetite or small orange wulfenite crystals. Cerussite pseudomorphs after descloizite are also known. Cerussite is abundant in twinned crystals, adjacent to and often covered with plattnerite. A large cerussite crystal weighing 500 grams was collected in 1970 (Minrec 54.3.383-408).
Cerussite from the Nakhlak Mine - Image
At the Tsumeb mine, Oshikoto Region, Namibia, some specimens of mimetite and cerussite rank among the finest in the world. Both are secondary minerals formed from pre-existing lead minerals, the cerussite forming first, probably from the weathering of galena. Then the mimetite crystallised on the cerussite, after which the chemistry of the environment changed to dissolve away the cerussite, leaving an epimorph of mimetite; some specimens retain a solid cerussite core, others have only residual cerussite, while still others are devoid of cerussite altogether. Some specimens retain clear evidence of original twinning. Associated minerals, other than goethite and hematite, are relatively rare. One large pocket produced an abundance of distinctive specimens in which the cerussite was incompletely coated with powdery yellow mimetite and was associated with calcium-rich duftite (R&M 96.4.352-357 ). Other minerals that form pseudomorphs after cerussite include arsentsumebite, hydrocerussite and smithsonite (R&M 96.4.352-357 ). Also cerussite pseudomorphs after anglesite have been found (KL p172, 205).
Cerussite from Tsumeb - Image
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 Palabanda quarries, Mfouati, Mfouati District, Bouenza Department, Republic of the Congo, "snowflake" cerussite is associated with malachite (Dr Marco Tam Shing Yau, The Mineralogy Society of Hong Kong Newsletter 19.8).
At the Mariquita Mine (Sultana Mine), Usagre, Badajoz, Extremadura, Spain, cerussite has been found very sparsely associated with galena; it forms colourless to white twinned crystals to 3 mm, associated with cinnabar, altered galena and secondary mercury and copper minerals (MinRec 55.4.496).
Cerussite from the Mariquita Mine - Image
At the Barrow Mine, Above Derwent, Allerdale, Cumbria, England, UK, cerussite has been found on a galena and quartz matrix with abundant white to yellow coloured cerussite crystals and micro-acicular pyromorphite crystals (AESS).
Cerussite from the Barrow Mine (AESS) - Image
At Force Crag Mine, Coledale, Above Derwent, Allerdale, Cumbria, England, UK, a small specimen of galena has been found with a dense coating of cerussite formed into ingrown crystals in a vug. In another specimen, an open face of matrix is covered with a combination of matte black sphalerite, white cerussite and typical brownish pyromorphite (AESS).
Cerussite from the Force Crag Mine - Image
At Red Gill Mine, Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK, a specimen was found with vugs containing a combination of cerussite, malachite and brochantite crystals with light blue chrysocolla. Another specimen featured cerussite associated with leadhillite (AESS).
Cerussite from the Red Gill Mine - Image
At the Old Brandley Mine, Catbells, Keswick, Allerdale, Cumbria, England, UK, a specimen has been found with a micro-crystalline quartz matrix with a dense coverage of galena crystals showing advanced stages of alteration to cerussite crystals (AESS).
Cerussite from the Old Brandley Mine - Image
At the Clargillhead vein, Garrigill, Alston Moor, Eden, Cumbria, England, UK, cerussite is the most abundant supergene phase, commonly directly replacing galena but also as crystals infilling void spaces. The earliest cerussite occurs as replacement rims on galena. Close to the galena this cerussite is dark-coloured with minute inclusions of either galena or yarrowite. It is commonly overgrown by pale coloured, inclusion-free cerussite. This type of cerussite also forms euhedral, acicular to tabular crystals infilling void spaces. Locally, 60 to 200 micron diameter cerussite crystals carrying fine-grained copper sulphides are present in galena (JRS 23.51).
The Sunnyside Deposit, Whitwell, Bolsover District, Derbyshire, England, UK, is hosted by late Permian (256 to 248 million years ago) dolostone that lies above a thick sequence of Carboniferous (354 to 290 million years ago) Coal Measures sediments.
Cerussite occurs as dark resinous crusts around galena and as rare crystals in cavities in baryte. It has a pale yellow fluorescence in long wave UV. One specimen was found with a striated blocky 565 mm cerussite crystal in a cavity with partly oxidised galena, overgrown by smaller rounded tabular crystals and locally coated in translucent, pale grey smithsonite (JRS 24.37-59).
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 Roar Hill, Ballater, Buchan Grampian, Scotland, UK, lead-bearing vein mineralisation was exposed during recent work carried out on an unmetalled vehicle track. A small temporary quarry exposed fluorite-bearing quartz veins and minor wulfenite in light-coloured granite. At a second site, a little further to the west, an oxidised galena-bearing quartz vein was exposed.
Cerussite occurs as a white overgrowth on partly corroded galena crystals in vein quartz at the track exposure (JRS 22.32).
At the Potter-Cramer property, Maricopa County, Arizona, USA, cerussite occurs as colourless crystals that fluoresce bright yellow under long wave UV. 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).
At the Tintic Mining District, Juab County, Utah, USA, cerussite occurs in every one of the major ore zones and in all of the large producing mines. It occurs in a wide variety of habits and colours, although it is most commonly white or pale yellow, and transparent. It can form elongated prismatic crystals and stubby, pseudo-cubic, highly modified crystals; some specimens consist of intergrown crystals forming “jackstraw” masses. Granular cerussite was not uncommon. Cerussite crystals range in size from less than a millimetre up to several centimetres. Granular or massive cerussite is found in great part directly replacing massive galena and it invariably contains silver (MinRec 55.2.187-190).
Cerussite from Tintic - Image
Alteration
In the oxidation zone of epithermal veins primary galena 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).
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).
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).
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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