So, i want to make a mod that involves ores. I already did all the pictures and colors for it,But i don't know how to make it underground and spawnable, So could anyone help me make this mod?? iIl give you credit after i'm done with it.Oh and i haven't really come up with a name of the ore, but it's not a ore that is real in Earth (it's a made up ore)

Thank you for your time