Better tools such as drill bits, end mills and other cutters are made out of HSS not carbon. (High speed steel) I believe you can do good selling this if its sorted as such and you can find a place to buy it.
Solid carbide drills are rarely found, usually tipped. They are silver soldered to the body, can of course de solder them.
Inserts for lathe and mill tools are usually carbide, but be careful there are steel ones!
And yes, carbide is heavy, darker colored. Don't use a file to test it won't tell you anything as it can not touch HSS either, a grinding wheel is better, but grinding it is hazardous!
Also Carbide is slightly magnetic.