Following on from my earlier post which posed the question as to what I had been photographing, heres the answer: decorative glass tiles!
These tiles are 2" square and about 3/4 " inch thick, with foil embedded in the reverse. The photos were shot with a macro close up lens, focussed on the edge of the tile, looking inside across the material immersed in the glass.
Dirt, dust and imperfections in the glass itself add to the effect, such as the large shard of green bottle glass which reflects and catches light on the scratches and facets.
The Martian plain shot is the underside of an old oyster shell, with worm casts and other flaws showing in the shell.
This last shot shows three tiles stacked up on each other, with the glue visible and the flaws and dyes showing in the glass. Shooting close up, shows the light bouncing between the two sufaces, reflecting off the material inside.