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

Apatite from dinosaur bone remains is represented by a carbonate-fluorine variety 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 characterized by the formula (Ca_9.08 Na_0.53 K_0.04...)_10.00 (P_4.28C_1.07Si_0.38S_0.32) _6.05(F, OH, Cl)_2.50. The replacement of phosphorus was effected simultaneously by: 1) the ellestadite scheme: 2P⁵⁺←(Si⁴⁺ + S⁶⁺), and 2) P⁵⁺ ←C4+ with the simultaneous replacement of Ca by (Na+K) and O^2- by F^1-. Other isomorphic effects are related to a replacement of Ca by divalent and trivalent cations, among which REE and Y play the important role. The enrichment of apatite in CO₂ is accompanied by decrease in density, refractive indices, 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 substitution of biogenic hydroxy-apatite and organic bone phosphate during the early diagenetic fossilization of dinosaur bone remains. This process was accompanied by the enrichment of diagenetic apatite in Si, S, C, F, Na, REE, Y, Sr, and Ba.