10.19. Operators ceasing, at any time and otherwise than in the circumstances described in section 10.18, to actually use in their mining operation a class 1 property, a class 1A property, a class 2 property or a class 2A property, or to regularly use in their mining operation a class 3 property, a class 3A property, a class 4 property or a class 4A property, are deemed to alienate the property at that time for proceeds of alienation equal to the lesser of the fair market value of the property at that time and its capital cost at that time and to reacquire it after that time for a capital cost equal to those proceeds of alienation.