Machinery and equipment purchased and used by mining or quarrying operations are exempt from the tax if the requirements of GR-55 are satisfied. The exemption may be claimed only for machinery and equipment utilized for the actual mining or quarrying operation itself which may include machinery and equipment used to wash, grade and separate the mined or quarried articles of commerce if such operation is carried on at the same site and as part of the continuous mining operation. Dump trucks or other transportation vehicles are not exempt from the tax.