Journal
AMERICAN MINERALOGIST
Volume 95, Issue 7, Pages 946-952Publisher
MINERALOGICAL SOC AMER
DOI: 10.2138/am.2010.3485
Keywords
Enthalpies of mixing; fluorapatite; chlorapatite; thermodynamics
Categories
Funding
- Earth Sciences Division of the U.S. National Science Foundation [EAR-0408829]
- Directorate For Geosciences
- Division Of Earth Sciences [1019809] Funding Source: National Science Foundation
Ask authors/readers for more resources
Solution calorimetric measurements have been made on 17 synthetic fluorapatite-chlorapatite crystalline solutions at 50 degrees C in 20.0 wt% HCl under isoperibolic conditions. Analysis of the calorimetric data indicates that heats of mixing across the series may reach values as high as 8.3 kJ/mol. Normally such a high degree of thermodynamic nonideality would be associated with immiscibility, yet no such miscibility gap is indicated by either synthetic or natural fluor-chlorapatite specimens. Based on full chemical analyses, all Cl-rich samples (X(Cl) > 0.65) of this study have halogen deficiencies that imply the presence of 4-11 mol% vacancies in the anion sites, which are interpreted to be associated with oxyapatite substitution. Separate analysis of data for the vacancy-free samples produces a linear fit for enthalpy of solution vs. composition, which yields an alternative interpretation of thermodynamic ideality. Together these models define the limits of enthalpy behavior for the fluor-chlorapatite system.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available