Apatite from dinosaur bone remains (the Gobi Desert, south Mongolia)

Apatite from dinosaur bone remains is represented by a carbonate-fluorine v ariety enriched in S, Si, Na, REE (up to 0.87%), Y, Sr, and Ba. The apatite which especially is enriched in CO2 (4.85%) and F (3.99%), is characterize d by the formula (Ca9.08Na0.53K0.04...)(10.00) (P4.28C1.07Si0.38S0.32)(6.05 )(F, OH, Cl)(2.50). The replacement of phosphorus was effected simultaneous ly by: 1) the ellestadite scheme: 2P(5+) <--(Si4+ + S6+), and 2) P5+ <-- C4 + with the simultaneous replacement of Ca by (Na + K) and O2- by F1-. Other isomorphic effects are related to a replacement of Ca by divalent and triv alent cations, among which REE and Y play the important role. The enrichmen t of apatite in CO2 is accompanied by decrease in density, refractive indic es, and the parameter a of the unit cell, and an increase in the parameter c of the unit cell. We conclude that carbonate-fluor-apatite formed as a result of the substitu tion of biogenic hydroxy-apatite and organic bone phosphate during the earl y diagenetic fossilization of dinosaur bone remains. This process was accom panied by the enrichment of diagenetic apatite in Si, S, C, F, Na, REE, Y, Sr, and Ba.