Idaho Code § 47-1205

The term “valuable mineral” for purposes of this act, shall be deemed to include not only gold, silver, copper, lead, zinc, coal, phosphate and limestone, but also any other substance not gaseous or liquid in its natural state, which makes real property more valuable by reason of its presence thereon or thereunder and upon which depletion is allowable pursuant to section 613 of the Internal Revenue Code, provided, however, that sand and gravel are not included in this definition.