Comparison of radon diffusion in the granular phosphate and in the corresponding powder

Moroccan sedimentary phosphates contain 50 to 200 ppm of uranium in partial radioactive equilibrium and therefore are radon emanation sources. They contain 60 to 80% of apatite (Berrada et al. 1995).

Recent studies of sedimentary phosphates (Berrada et al. 1995), of fossil bones and dentine (Berrada et al. 1995; Michel et al. 1995 & 1996; Allard et al. 1997; Reyes et al. 1999) and other natural apatites (Weber, 1982) show some chemical and structural changes between them.