That would be incorrect. Unless you or a previous owner has specifically relinquished any of the rights to your property, you still possess all of them, mineral rights included.
In California, "real estate" is the same as "real property" and includes land, fixtures to land, anything incidental or appurtenant to land, and anything immovable by law.
Incidental rights (as used above), includes air rights, surface rights, subsurface rights, mineral rights, water rights, riparian rights, littoral rights, and underground water rights.
Few people take the time to actually get a copy of their deed and covenants and read them through. It's not that hard to do and I would recommend you do so. If you (TGF) need help doing this in Santa Clara County, Freepmail me.
--Boot Hill
The United States considers itself sovereign over California, so unless you have a specific mention of mineral rights in your title, you likely have NO mineral rights.
Examples of this are especially seen all through California concerning oil and water.
You can't in most places dig a well without paying for your own water to the local water company who leased the water rights from the State or Federal government.
Though I can't post scripture and verse here regarding the exact law, I have an additional memory that there were laws passed between 10-20 years ago that further eroded personal property rights at least in California.
I think that if you find oil on your own property, you may find it difficult or impossible to drill yourself for it.
There are some older personally owned properties with grandfathered water or oil wells that have retained some form of use or commission. I think they are like being legal non-conforming.
Granted, you have a certain level of airspace rights. This is most noticeable in areas like beaches where there is the view and people who built homes at lower levels near the beach in front of other homes might sell their airspace rights to their neighbors so the neighbor can build up and be guaranteed not to lose their view.
In general, I think California residents mineral rights have been vastly eroded over the last three decades, mostly by laws.
PS: I don't like it.
In addition, new laws may override titles with various rights, covenants or restrictions.
On the surface this seems impossible, but it happens in fact.
One grand example of this in California are all the titles with the restriction that you may never sell to a black person. The old racist stuff like that are null and void, and though mineral rights are not racist or similar in theory, the fact is mineral rights are valuable, and the government has done all it can to restrict your rights in recent decades.