Aragonite-Strontianite-Calcite solid solution

[MichaelZ20]

Dear colleagues,
I wonder what will be a change in Sr concentration in solution contacting with Aragonite-Strontianite solid solution when Aragonite is gradually replaced by Calcite.
Isn't it too coarse approximation to consider two binary solid solutions (Aragonite-Strontianite and Calcite-Strontianite) with changing mixing portions of the components?
Thank you in advance for your reply.
Sincerely,
Michael

[dlparkhurst]

While aragonite and strontianite are both orthorhombic crystals, calcite is not. Glynn (2000, https://www.researchgate.net/publication/259218116) lists nonideal solid solution paramters for aragonie/strontianite, but none are listed for Sr in calcite. So, I expect Sr would be released in the process of converting aragonite to calcite, with little Sr taken up in calcite. Without too much investigation, that would be my hypothesis, but perhaps a more thorough literature search is warranted if it is a critical issue.

[MichaelZ20]

David, thank you!
In an exercise in the book of Appelo & Postma (p. 152) Guggenheim's parameters 5.7 and 0 are mentioned for calcite-strontianite solid solution.