Well, I was experimenting with images of ores, and I edited out all the mineral part. I was left with stone with holes in it. I put sand behind it, and it had the same shaded and light spots on it as the ores. If you recolor the sand to be blue, it makes diamond ore...so I think that Notch edited out bits of the stone, then put sand behind it, and recolored it. BOOM ORES
All the ores are just recolored versions of coal.
Which is just sand turned black put behind the stone texture.. :/
This.