A friend recently made me aware of a publication by the Real Estate Center at Texas A&M called "Mineral Law West of the Pecos," written by Judon Fambrough, a lawyer who is with the Center. Judon has written much good stuff about land and mineral law in Texas, and this publication is no exception. (The Center has many good articles and publications on its website of interest to land and mineral owners.) Judon's article contains a good summary of the history of land grants in West Texas, mineral reservations, the Relinquishment Act and "mineral-classified" land, what constitutes a "mineral," and recent litigation over State ownership of minerals in West Texas. His article is well written and informative and should be in every oil and gas lawyer's library. The law of Texas land grants in West Texas (and South Texas) is complex and fascinating.
Judon provides this link to maps online at the Texas General Land Office, which show tracts in West Texas subject to any mineral classification or reservation by the State:
Another good resource.