Last night, I had a flash of insight about how to implement crossed polarizers when shooting macro using the larger Luminars (100mm and Zoom), here are some results. All images are full frame 35mm format.
thin section of Harzburgite, using 100mm Luminar:
Switching over to Zoom for larger field of view, starting with a thin section of agate:
Next is a thin section of "limestone with coral", looking rather sinister...
And last is a section of pine wood: