Hello Brian,
Thank you kindly for your reply. I played with delxi to get the program to converge on an answer (after 300000 steps!), but it didn't seem like the right answer- there were far too many minerals saturated, and the pH was very high. Thinking that we didn't take into account some clay phases that might be forming in the stockpile, I unsuppressed them in the next run. Now, once again, the program can't find a solution, and says the Xi step is too small. I am attaching the script because I wonder if there is something I am missing. Any insight you have would be much appreciated!
Thanks, Allison
stockpile_121912.txt