The decision of the Appellate Tax Board dated August 13, 1991, was correct for the reasons stated therein. The concept advanced by the taxpayer that its portable stone-crushing machines should be regarded as industrial plants having a succession of fixed locations at the quarries where they are employed for various periods of time would make nonsense of the amendment to G. L. c. 64H, § 6(s), effected by St. 1971, c. 555, § 45, when the concept of “industrial plant” in § 6(s) was confined to “a factory at a fixed location. . . .” This amendment was in apparent response to Wakefield Ready-Mixed Concrete Co. v. State Tax Commn., 356 Mass. 8, 10-12 (1969), which had held that cement mixer trucks should be regarded as “industrial plants” within the meaning of § 6(s) (thus making replacement parts exempt from the sales and use tax) despite their mobile character.

Decision of Appellate Tax Board affirmed.