What resources do C-Type asteroids contain? The research I've done has come up with carbon, but what form is the carbon in? Graphite, diamonds, coal, or some other material?
Carbonaceous asteroids contain carbon in the form of chondrites (small marble-sized nodules),tiny crystals and other sorts of carbon dust. This is mixed in a sort of conglomerate with dust and nodules if silicate material, sometimes even nickel-iron nodules. What resources do they contain? They don't contain diamonds, because diamonds require enormous heat and pressure to form, so sometimes micro-diamonds are found in the craters of large meteorite impacts on Earth. Some of them probably contain valuable materials, but they would have to be very valuable indeed to be worth the trouble and expense of retrieving them from the asteroid belt. Prospectors there wouldn't restrict their attentions solely to carbonaceous types, and would probably explore large asteroids like Ceres. Asteroids and meteorites couldn't possibly contain coal, which is a biological product formed from thick layers of plant debris transformed by heat and pressure over millions of years in the bowels of the Earth.