Would the mineral rights deed be recorder somewhere in the Fresno county records? If the mineral right were passed down to a relative where would this document be recorded?
The short answer is yes, mineral rights deeds are recorded in the county in which the mineral rights are held. There are often deeds, however, that are not recorded. They are valid as between the grantor and grantee and their heirs but are difficult to find since they are typically held in someone's possession. In addition, the failure to record a deed does not put others on notice that a transfer occurred. You can conduct an online grantor/grantee of documents recorded in Fresno County. Unfortunately, you cannot review the documents online unless you have access to a particular software program. Thus, you'll have to go to the recorder's office to view the documents to see what property was granted.
Good luck!