(one of) the possible sources from what I've heard/read: H chondrites--> asteroid 6 Hebe Aubrites--> 1303 Eger Enstatites--> 21 Lutetia Mesosiderites--> 4 Vesta Please keep in mind that I am not stating this as fact. I'm not interested in debating this. You can find this info. simply by Googling or visiting Wikipedia..