Welcome Andrea and family,
Educate yourself on how to claim mineral rights on properties.
If you dont, you will likley spend monies more than is needed
and waste alot of time.
Once you understand what and how to file a claim, its easy
Do not go to BLM, until you have filed with the county in which the claim is within, in California
If considering buying an existing claim,
research, sample, investigate proper fee's and filings are in place with the COUNTY, before laying down a dime.
Counties are law no matter the land in which it lies
As for others laying claim to minerals already claimed, is called claim jumping
This is where the bogus co. come in, hoping the prospective buyer wont bother doing their due diligence before laying down the $$$
Doing unauthorized mining on a claim that you do not belong on is called high grading, not claim jumping.
So much to learn, keep at you will
So Much River So Little Time...Get Out There