(1) A mine which has been opened on a date before the commencement of this Act (not being a date that falls more than 7 years before such commencement) shall not be rateable until the year after the year in which the mine shall have been opened for 7 years.

(2) An abandoned mine which has been reopened on a date before the commencement of this Act (not being a date that falls more than 7 years before such commencement) shall not be rateable until the year after the year in which the mine shall have been reopened for 7 years.

(3) A right to drill for and take away petroleum in respect of a particular oil pool, being a pool from which oil was first produced on a date before the commencement of this Act (''the date of first production''), not being a date that falls more than 20 years before such commencement, shall not be rateable until the 20th year from the date of first production.

(4) An apartment -

(a) which ceases to be used as part of an apart-hotel for a period of 12 months or less, and

(b) which, but for this subsection, would not be rateable during that period by reason of its being a domestic premises,

shall be rateable during that period, unless otherwise exempted from being rateable by virtue of this Act.