The stones are basically calcite and in thin section are quite transparent. The marble shows a lot of birefringence, but is deficient in interference colours.
Composite photo 1 shows the original stones with a full scan of the thin section and two selected areas.
As the marble thin section looks rather flat, I decided to spice things up a bit.
Composite photo 2 shows a bit more life.
I placed the slide on the vintage Baush & Lomb and put a blue/yellow Rheinberg filter in the holder.
Moving the filter holder into the light path, the edge of the filter holder produced a pseudo oblique lighting effect . As the filter was moved further into the light path, the edge of the Rheinberg filter started to affect the image.
