With the manufacturing procedure of "rough-honed" the natural grain of the surface is grinded.
By grinding the surface, the stone becomes easier to clean and is considered to be an optical improvement.
When looking at the Solnhofener Stone, there are sometimes ‘quartz veins’ which appear to run through the stone like a thread.
These originate from millions of years ago when earthquakes caused fissures in the mountains which were then filled with semi fluid chalk and other minerals. These minerals were subjected to tremendous pressure as the earth cooled and in turn formed the Solnhofener Stone that we know today.
Some people mistake these veins for faults or cracks filled with glue or filler, but in reality these veins are a natural phenomena and in no way influence the strength of the stone. These materials are naturally bound together and the ‘quartz veins’, together with the fossils are a natural characteristic of this stone.