18. The following expenses may be included in an investment allowance under section 17:
(a) the cost to the operator of a property specified by regulation that is actually used by him in the production of materials that are mainly products derived from certain ores;
(b) the cost to the operator of allowable depreciable property actually used in the processing or treatment of ore to the prime metal stage or its equivalent, if an allowance in respect of that property has never been taken previously under this division by any person and the property was so used for a period of at least twelve consecutive months during which it was not used for other purposes more than 25 per cent of the time;
(c) the mining exploration expenses incurred by the operator in Québec on lands other than those which are the site of the principal mining operation, to the extent that, under paragraph n of section 8, those expenses were deductible in computing his annual profit for a previous fiscal year, or are so deductible for the fiscal year contemplated; and
(d) the mining exploration and development expenses incurred by the operator in Québec, from 28 March 1979, on the site of an underground mining operation, except the expenses incurred by an operator principally extracting from an iron ore, titanium or asbestos mine and the cost of the property contemplated in Division II of Chapter III, provided that a detailed analysis of these expenses is submitted to the Minister.