Thanks for both your replies.
I was a bit confused, because Unused12 looked like limestone to me. I don't think Unused12 has any connection with Marble, because Unused12 occupies ID 27 (decimal) in all versions. Cleopatra added the goods Oil, Henna, Paint, Lamps, blocks of Marble between IDs 31 and 36 and then continues with the goods from the previous Pharaoh version. On the other hand, Unused12 comes directly after the other block goods.
I mean, it might have a connection, but there is just not good enough evidence. That wiki doesn't like speculations be added. :P
If I edit a good in a storage yard to be gold, it shows up as gold (after reloading the savegame).
Looks like it can behave like a good but is disabled in Pharaoh. (unless it isn't in some custom map. I have to investigate.)
So about buildings: Looks like the devs wanted to implement Mud and Brick versions of defensive structures, possibly with Brick versions costing bricks to build. But then they scrapped it. They also wanted to add a Senet Master building which spawns a walker (senet master) that goes to Senet Houses and runs them.
Thanks for your help, again
Edit:
How can I view .sg3 and .555 files?[This message has been edited by mugg91 (edited 01-10-2017 @ 07:19 PM).]