Chlorite can often be found replacing micas. Sometimes I have a hard time noticing it in cross-polar in the first place, given the drastic shift in birefringence colors. Thankfully, plane-polar's got my back.
I just realized after- *looks at calendar* -however long I've been a geologist, P-T diagrams have given me so much trouble because they're in fact NOT space-time diagrams and you do not put them into geologic context, you just kinda. Stare at them.