Natural Resources Code §71.009

(a) In each lease other than a lease for coal and lignite executed under this subchapter, the lessor shall retain at least a one-eighth royalty. (b) In a lease for coal and lignite executed under this subchapter, the lessor shall retain at least a royalty based on one of the following or a combination of the following: (1) a sum certain per ton; (2) a percentage certain of the gross sale price F.O.B. at the mine site of the coal and lignite; or (3) a sum certain for each acre-foot of coal and lignite mined and removed from the premises. (c) Royalties under a coal and lignite lease may be paid as advanced mineral royalties.