Experimental study of the system fluorapatite-chlorapatite under 10 and 12 kbar at 640, 750 and 900°C

Abstract

Fluorapatite (FA), chlorapatite (CA), and five intermediate members (FA₉₀CA₁₀,FA₇₀CA₃₀,FA₅₀CA₅₀, FA₃₀ CA₇₀ and FA₁₀CA₉₀) were synthesized by mixing appropriate chemicals. The mixture were subjected to following P-T conditions: 8 kb-640°C, 10kb-750°C and 12kb-900°C. A complete solid solution between two end members could be established from refractive index and cell parameter measurements. A plot of the F-CI contents vs composition of the starting materials show a gradual decrease in F with increase in CI content and a negative slope. A careful study of aptites from nature should reveal a continuous spectrum from F-rich to CI-rich apatite.