Make a Rb/Sr isochron diagram using excel and calculate an isochron age and fit of the line assuming that all minerals crystallized simultaneously. ___________________________________________________________________________ Hello. I am working on Geochemistry Homework. I need help with #2 withcalcuate an isochron age and fit of the line assuming that all minerals crystallized simultaneously.I also uploaded my work. I made the chart for my data. I uploaded the assignment so you can read the directions and my work.