I encountered the stuff in the 80's, overseas. It sure looks interesting. As the picture suggests, you can easily pick up a block that, from a short distance, looks like you would need a forklift to move.
The texture is rather rough .... sort of like the scouring blocks restaurants use to clean their griddles. You can very easily cut it, carve it, etc .... often using another piece as your 'tool.' Yet, it has the same compressive strength and fire resistance of 'regular' blocks.
Overseas, it was common to use one of these to make chases for your wires:
http://www.masterwholesale.com/details/1190749723.htmlOr, a rotohammer with a chisel bit was used to carve a slot.
The wiring method was similar to our "smurf tube." Slots were simply mortared over.
As I read our NEC, if you did that here, you would need to have 1/8" of steel to protect the wires, as the slots aren't quite deep enough.
