(a)    In this subtitle the following words have the meanings indicated.

(b)    “Mineral” includes:

(1)    Gas;

(2)    Oil and oil shale;

(3)    Coal;

(4)    Gaseous, liquid, and solid hydrocarbons;

(5)    Cement materials, sand and gravel, road materials, and building stone;

(6)    Chemical substances;

(7)    Gemstone, metallic, fissionable, and nonfissionable ores; and

(8)    Colloidal and other clay, steam, and geothermal resources.

(c)    “Mineral interest” means an interest in a mineral estate, however created and regardless of form, whether absolute or fractional, divided or undivided, corporeal or incorporeal, including a fee simple or any lesser interest or any kind of royalty, production payment, executive right, nonexecutive right, leasehold, or lien in minerals, regardless of character.

(d)    “Severed mineral interest” means a mineral interest that is severed from the interest in the surface estate overlying the mineral interest.

(e)    “Surface estate” means an interest in the estate overlying a mineral interest.

(f)    (1)    “Surface owner” means any person vested with a whole or undivided fee simple interest or other freehold interest in the surface estate.

(2)    “Surface owner” does not include the owner of a right–of–way, easement, or leasehold on the surface estate.

(g)    (1)    “Unknown or missing owner” means any person vested with a severed mineral interest whose present identity or location cannot be determined:

(i)    From the records of the county where the severed mineral interest is located; or

(ii)    By diligent inquiry in the vicinity of the owner’s last known place of residence.

(2)    “Unknown or missing owner” includes the heirs, successors, or assignees of an unknown or missing owner.