The 1876 Texas Constitution, because the Constitution actually supports the owners
“the state released to the owner of the soil all mines and mineral substances therein”
This constitutional provision had retrospective effect; the landowner was given complete ownership of the minerals in all lands that passed from the sovereign before the effective date of the Constitution of 1876. , and what Many mistakes in the text about mineral rights but the reference is about taxation, not the surrender of land.
The Texas Supreme Court in 1928, in Greene v. Robinson.
Rather than holding the Relinquishment Act unconstitutional, the Court “construed” the Act in a way that would pass constitutional muster. It held that the Act did not relinquish the oil and gas to the landowners; instead, it made the landowners the agent of the State for the leasing of oil and gas rights, and granted to the landowner the right to one-half of all bonuses, royalties and other benefits accruing from those leases.
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Texas entered the Union retaining all of its public domain – all land not already sold by Spain or Mexico to private citizens. Under Spanish and Mexican laws, when the sovereign sold land it retained all mineral rights under those lands. When Texas became an independent nation, it recognized the titles of landowners who had acquired their lands by Spanish and Mexican grants, including the state’s retention of mineral rights under those lands. In its constitution of 1876, Texas set aside more than 42,500,000 acres of unsold land as “public free school land,” and provided that the sales of those lands would be set aside in a permanent fund to finance the provision of schools in Texas. That constitution also provided that the State released to the owners of lands previously sold “all mines and mineral substances” under their lands. This same provision was included as an article in the Revised Statutes of 1895. Thus, Texas decided that, unlike Spain and Mexico, it would not retain title to minerals under lands it sold for settlement and development.