Carbon to Iron ratio

As any other blacksmith (or machinist) you can get an idea by using a grinder. More sparks means more carbon.

Scientifically, all I can think of is to use a small sample and a very accurate scale to determine the weight, then just as accurately find its volume. Then derive its density. Compare that to the density of Fe and any variance will be your impurities (C). Unless your sample is pure carbon and iron, it may not tell you exact carbon, but it might help.

Drew