Wyoming Constitution Art. 15, § 3. Taxation of mines and mining claims

All mines and mining claims from which gold, silver and other precious metals, soda, saline, coal, mineral oil or other valuable deposit, is or may be produced shall be taxed in addition to the surface improvements, and in lieu of taxes on the lands, on the gross product thereof, as may be prescribed by law; provided, that the product of all mines shall be taxed in proportion to the value thereof.