What are the risks associated with purchasing this new construction property in Placer county? Title report questions.

In escrow for a brand new construction in Placer county and title report indicates as follows: Can you share if the verbiage indicates that these heirs can just come into my cousin's property and start mining? What exactly are the risks with buying this land on which third parties have the said interest as the legalese is very hard to understand for laypersons like me? Thank you! Title policy exceptions: EXCEPTING THEREFROM, an undivided 1/4 interest in and to all oils, mineral and other hydro-carbon substances lying in or under said land, as reserved by XYZ and ABC, husband and wife, in Grant Deed recorded on February 2, 1953, in Book XXX, Page XXX, Official Records; * Under exclusions, title policy states as follows: Rights incidental to the ownership for the use and development of the mineral rights reserved in Deed executed by XYZ and ABC recorded February 2, 1953, Book XXX Page YYY of Official Records.