I was inspired by the art @BCanning did on ceramic tile so I found a cheap piece of 3x6 inch white marble tile and tested how much detail I could capture on it.
After playing around with marble tiles a little more I think I am getting the settings figured out. this is a 6x6 inch polished marble tile (about fifty cents at my flooring store). Engraved at 155 mm/sec with 45% power (of 65 watts). Then sprayed with black template paint and used mineral sprints to remove excess.
All text and images were pulled from US Patent page and scanned using threshold processing.