; (2) by inserting mineral materials, including but not limited to after varieties of in the first sentence; (3) by striking or cinders and inserting in lieu thereof cinders, and clay ; and (4) by adding the following new subsection at the end thereof: (b) (1) Subject to valid existing rights, after the date of enactment of the Hardrock Leasing and Reclamation Act of 2018 , notwithstanding the reference to common varieties in subsection (a) and to the exception to such term relating to a deposit of materials with some property giving it distinct and special value, all deposits of mineral materials referred to in such subsection, including the block pumice referred to in such subsection, shall be subject to disposal only under the terms and conditions of the Materials Act of 1947. (2) For purposes of paragraph (1), the term valid existing rights means that a mining claim located for any such mineral material— (A) had and still has some property giving it the distinct and special value referred to in subsection (a), or as the case may be, met the definition of block pumice referred to in such subsection; (B) was properly located and maintained under the general mining laws prior to the date of enactment of the Hardrock Leasing and Reclamation Act of 2018 ; and (C) was supported by a discovery of a valuable mineral deposit within the meaning of the general mining laws as in effect immediately prior to the date of enactment of the Hardrock Leasing and Reclamation Act of 2018 . . (b) Mineral materials disposal clarification Section 4 of the Act of July 23, 1955 ( 30 U.S.C. 612 ), is amended— (1) in subsection (b) by inserting and mineral material after vegetative