Tex. Nat. Res. Code § 52.171

The state hereby constitutes the owner of the soil its agent for the purposes herein named, and in consideration therefor, relinquishes and vests in the owner of the soil an undivided fifteen-sixteenths of all oil and gas which has been undeveloped and the value of the same that may be upon and within the surveyed and unsurveyed public free school land and asylum lands and portions of such surveys sold with a mineral classification or mineral reservation, subject to the terms of this law. The remaining undivided portion of said oil and gas and its value is hereby reserved for the use of and benefit of the public school fund and the several asylum funds.