(1) One-half of the contract sales price of coal sold by a coal producer who extracts less than 50,000 tons of coal in a calendar year is exempt from taxation.
(2) Metal mines producing less than 20,000 tons of ore in a taxable year are exempt from property taxation on one-half of the merchantable value.
(3) The first 1,000 tons of travertine and building stone extracted from a mine in a tax year are exempt from property taxation.
(4) Bentonite extracted from a mine is exempt from property taxation.