Limestone with diatoms in-situ from Norway. Thin rock section. Prepared by Edmund Wheeler. Olympus BHB microscope using 450nm LED light. 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, brightfield lighting (technically this is plane polarized light, as there was a linear polariser above the photoeyepiece).2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Single images, no stacking. I did also try cross polarized, but it didn’t make things clearer, so stuck with these ones. Three locations on the slide shown.