This will help you see the data for your region. Keep in mind that a person's land may be quite different.
https://mrdata.usgs.gov/geochem/doc/averages/countydata.htm
The one thing that I think is really overlooked is the recommendation of your breeder!
You can read all the books you want, get all the info etc BUT if you go to a good breeder then pay attention to their program. Once you get experience you can try different things but be careful not to do just whatever you read. Region makes a big difference as well. The quality of hay, the parasite differences, type land, etc.
We give very good instruction and generally give a 3-4 hour class on goat care to all newbies. We cover everything. Feed, minerals, we talk alot about stuff people read, and we explain what we do and WHY we do it.
@DellaMyDarling makes some VERY good points. (I really appreciated your post!) (BTW we have high iron well water that impacts copper but keep in mind, giving more can be an issue... the copper ends up being stored and that causes toxicity) There is a lady doing a lot of research on this with her Dwarf herd. Extensive. Molybdenum also plays a key role.
I will expand-
Client A follows all the breeders instructions, calls breeder with questions, learns goats and has healthy productive animals. Over time tries different protocols specific to their farm and develops their specific management style.
Client B starts out great but then gets all caught up in FB groups and crazy info stuff, goats aren't thriving, not breeding, not settling. WHY? Because client B "read" that ND's don't need feed... goats don't need feed... Went to a mineral bar that goats don't touch... Browse is best.
Client B's goats are now getting parasites, lacking selenium and not healthy but still "look" ok. 6 months later goat/s are dead.
Client B claims no vet in area yet a google search show 4 livestock vet within 1/2 hour. :/
Client B starts talking about the breeder of the goat and how it wasn't healthy to begin with... yet when pressed you find out Client B had the goat for 6 months from a 2 month old kid and hasn't been feeding, or cocci prevention, or fecals, or minerals etc.
Don't be client B!