ad  coelum  doctrine.The  common-law  rule  that  a  landowner  holds  everything  above  and

below  the  land,  up  to  the  sky  and  down  to  the  earth’s  core,  including  all  minerals.  •  This  rule

governs  ownership  of  “hard”  (immovable)  minerals  such  as  coal,  but  not  “fugacious”  (volatile)

minerals such as oil and gas. Cf. RULE OF CAPTURE. [Blacks Law 8th]