Looks more like an Ark to me. The bottom with the splitted material is very typical for Arks glued on wood or in a box. The troutstones do have some red or brown spots most of the time, because of the iron conten in the stone. But of course there are also plein white ones.
One typical difference of the Saxonian oilstones compared to translucent Arks is, that the oilstones are only translucent to a very small extent.
An example you see in the following picture, the translucent Ark below, where the light shines through the whole stone and the saxionian above, where the light only gets through the edges:
Attachment 314048
Even if you have a very thin example of the saxonian, you see that light is only going through the thin est part, where the stone gets thicker, it doesn't shine through:
Attachment 314049
Regards Peter