Pyromorphite structure

For example, narrow bands in pyromorphite luminescence spectra at 380 and 439 nm (Fig. 4.26) maybe connected with Pb emission. Two structurally... 

Laperche Traina (1998) studied Pb uptake on hydroxyapatite at low initial solution concentration of Pb (103 mg/L). For this, EXAFS was used to characterize the local coordination environment of Pb on the apatite. The baseline corrected, Fourier-transformed EXAFS spectra revealed fc-values at >3 A, suggesting that Pb was not randomly sorbed. Radial structure functions (RSF) showed three intense peaks, characteristic of pyromorphite. 

Dai Y, Hughes JM (1989) Crystal structure refinements of vanadinite and pyromorphite. Can Mineral 27 189-192... 

Curry NA, Jones DW (1971) Crystal structure of brashite, calcium hydrogen orthophosphate dihydrate A neutron-diffraction investigation. J Chem Soc 3725-3729 Dai Y, Hughes JM (1989) Crystal-structure refinements of vanadinite and pyromorphite. Can Mineral 27 189-192... 

Na + Si", but numerous other possibilities exist as many ions are acceptable in the apatite structure. The U content of natural apatite thus remains limited and vacancies or defects could also play a role in this substitution. Pb is accepted in the apatite structure producing the end member phase pyromorphite. Unfortunately, this isostructural substitution may lead to high Pb concentrations (Krogstad and Walker 1994). Thus, apatite, as with monazite, has little crystallographic tendency to behave as an open geochronometric system for U-Th-Pb. 

Lead phosphate has been identified by Winter (1981) on a fourteenth century Kamakura panel among examples of lead white q.v.) on Japanese paintings. Composition is given as Pb9(P04)g from coincidence of X-ray diffraction data and identification of lead(ll) and phosphate ions. No wholly equivalent natural mineral exists, though pyromorphite (Pb5(P04)3Cl), mimetite (Pb5(As04)3Cl) and oxypyromorphite (Pbio(P04)60) are the most closely related structurally. 

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