Activity diagram illustrating the relative stability of Pb-bearing minerals as a fuction of CO2 partial pressure (-log PCO2 = 3.52 is atmospheric) and the activity ratio, pH + 2 log Pb2+. The minerals that may potentially form in the soil near the lead pipe are displayed: alamosite, PbSiO3; calcite, CaCO3; cerrusite, PbCO3; hydrocerrusite, Pb3(CO3)2(OH)2; hydroxyapatite, Ca5(PO4)3(OH); hydroxypyromorphite, Pb5(PO4)3(OH); and litharge, PbO. The phase that is predicted to produce the lowest activity of Pb2+ (i.e., cerrusite) is the mineral predicted to be the most stable (for the stipulated conditions) and thus to control Pb2+ behavior in the system.

From The Horace's Villa Project, 1997-2003 by Bernard Frischer, Jane Crawford and Monica De Simone

Subjects
  • European: Ancient to 400 C.E.
Citable Link
  • Figure 20 Activity diagram illustrating the relative stability of Pb-bearing minerals as a fuction of CO2 partial pressure (-log PCO2 = 3.52 is atmospheric) and the activity ratio, pH + 2 log Pb2+. The minerals that may potentially form in the soil near the lead pipe are displayed: alamosite, PbSiO3; calcite, CaCO3; cerrusite, PbCO3; hydrocerrusite, Pb3(CO3)2(OH)2; hydroxyapatite, Ca5(PO4)3(OH); hydroxypyromorphite, Pb5(PO4)3(OH); and litharge, PbO. The phase that is predicted to produce the lowest activity of Pb2+ (i.e., cerrusite) is the mineral predicted to be the most stable (for the stipulated conditions) and thus to control Pb2+ behavior in the system.