Depends on the cable. basic cable is just high carbon steel, how high and what exact alloy depends on it's aplication, plow steel, improved plow steel, extra improved plow steel, extra extra improved plow steel, and there's bound to be special aplication cable out there that has some wierd alloys in it.
Also what makes the pattern in wire rope damascus is the decarb around the wires and the weld zone. The bigger the wire the more steel to iron ratio, the smaller the wire the more iron to steel ratio. I've never had one break like glass, but I've had sections break like glass a few wires at a time. Cable forge and heat treated rite is nearly unbreakable. The wires with there hard and soft layers go everywich way through the blade and to break it has to tear through the weld zone, break the hard layer, then tear through anouther soft zone. I don't know if RC'n is even posible. With large enough wires it will get very hard though.
