FWIW, I'm pretty sure that was wrought iron rather than cast. It's kinda streaky or fibrous in nature with a lot of silica impurities. Which makes it look AWESOME when used as knife guards or outer layers of san mai blades and heavily etched. It forges like butter at higher heats, but can split along the grain kinda like wood. Neat stuff. I've never seen it etched like that on a firearm.
