Magnesium's hairy stuff. We once distracted our entire high school chemistry class while our teacher lectured obliviously by sparking up a small piece of it on the Bunsen burner, realizing, much to our dismay, that we couldn't put it out because it even burns under water, so we just dropped it in the sink and let it burn itself out. One of Dan Gurney's rationales for the lack of seat belts in the Eagle F1 is that he figured it'd be better to be thrown clear of the car in a crash rather than be creamated in the car's magnesium tub.
But it's also very light, and a group in Australia has come up with a casting technique that they allege is porosity-free and uses permanent molds, allowing for tight tolerances time after time, which means less machining. They're currently focusing on wheels and engine blocks, which reportedly be substantially cheaper than equivalent-strength items created using older techniques. We're waiting for a replica of the magnesium cowl used on Buick's legendary, Harley Earl-styled LeSabre. Now that was trick.
Metal Magic: Creating Panels in the Midnight Sea via Hydroforming [Internal]