(1)In this Part references to aggregate—
(a)include references to the spoil, waste, off-cuts and other by-products resulting from the application of any exempt process to any aggregate; but
(b)do not include references to anything else resulting from the application of any such process to any aggregate.
(2)In this Part “exempt process” means—
(a)the cutting of any rock to produce dimension stone;
(b)any process by which a relevant substance is extracted or otherwise separated (whether as part of the process of winning it from any land or otherwise) from any aggregate;
(c)any process for the production of lime or cement from limestone or from limestone and some other substance.
(3)In this section “relevant substance” means any of the following—
(a)anhydrite;
(b)ball clay;
(c)barytes;
(d)calcite;
(e)china clay;
(f)feldspar;
(g)fireclay;
(h)flint;
(i)fluorspar;
(j)fuller’s earth;
(k)gems and semi-precious stones;
(l)gypsum;
(m)any metal or the ore of any metal;
(n)muscovite;
(o)perlite;
(p)potash;
(q)pumice;
(r)rock phosphates;
(s)sodium chloride;
(t)talc;
(u)vermiculite.
(4)The Treasury may by order made by statutory instrument—
(a)modify the list of substances in subsection (3) above by adding any substance to that list or by removing any substance from it; and
(b)make any such transitional provision in connection with the modification of that list under this subsection as they may think fit.
(5)The Treasury shall not make an order under subsection (4) above by virtue of which any substance ceases to be a relevant substance unless a draft of the order has been laid before Parliament and approved by resolution of the House of Commons.
(6)A statutory instrument containing an order under subsection (4) above that has not had to be approved in draft for the purposes of subsection (5) above shall be subject to annulment in pursuance of a resolution of the House of Commons.