Is it permissible for the Imam to grant land grants (Iqta') from apparent (surface) mineral deposits?

Primary text

It is impermissible for the Imam to grant land grants concerning apparent mineral deposits that cannot be revived (i.e., existing, uncovered resources). The evidence for this is the action of the Prophet, peace be upon him, when 'Ubayy ibn Hammal requested a grant of salt mines at Ma'rib. Upon realizing that he was only granting water (flowing resources), the Prophet revoked the grant. Furthermore, granting such common resources imposes undue restriction upon the Muslims.