Have you ever tried burning magnesium? I wasn't trying to burn it, but it happened anyway. I used to be in the asphalt paving business, and we used a tool called a lute to spread hot mix asphalt on driveways and parking lots in areas that were too confined to use paving machinery to do the job. These tools were made of aluminum, magnesium or some other light weight metal. It was necessary to clean asphalt from the tool after it had gotten cold, so we would have to clean it to remove the cold material before being able to use the tool again. We removed it by simply scraping it, unless it had gotten to cold and hard. Then we would have to heat it with burning gasoline or diesel. If it got too hot the magnesium would start sparkling and burning.