to any expenditure with respect to which a deduction is allowed or allowable under this section to the taxpayer. . (b) Conforming amendment The table of sections for part VI of subchapter B of chapter 1 of the Internal Revenue Code of 1986 is amended by inserting after the item relating to section 176 the following new item: Sec. 177. Deduction for purchase of critical minerals and metals extracted within the United States. . (c) Effective date The amendments made by this section shall apply to amounts paid or incurred after December 31, 2019. 4. Grant program for development of critical minerals and metals (a) Establishment The Secretary of the Interior shall establish a grant program to finance pilot projects for the development of critical minerals and metals in the United States. (b) Limitation on grant awards A grant awarded under subsection (a) may not exceed $10,000,000. (c) Economic viability In awarding grants under subsection (a), the Secretary of the Interior shall give priority to projects the Secretary determines are likely to be economically viable over the long term. (d) Secondary recovery In awarding grants under subsection (a) during a fiscal year, the Secretary of the Interior shall seek to award not less than 30 percent of the total amount of grants awarded during that fiscal year for projects relating to secondary recovery of critical minerals and metals. (e) Authorization of appropriations There are authorized to be appropriated to the Secretary of the Interior $50,000,000 for each of fiscal years 2021 through 2024 to carry out the grant program established under subsection (a). (f) Definitions In this section: (1) Critical minerals and metals The term critical minerals and metals means cerium, cobalt, dysprosium, erbium, europium, gadolinium, graphite, holmium, lanthanum, lithium, lutetium, manganese, neodymium, praseodymium, promethium, samarium, scandium, terbium, thulium, ytterbium, and yttrium. (2) Secondary recovery The term secondary recovery means the recovery of minerals and metals