THIS invention relates to a method and heap for recovering metal values from ore in a heap leach process. The method includes the steps of depositing and stacking crushed ore 16 on an impermeable pad 12 to form a heap, and enclosing the heap with a substantially impermeable coating 18 to both gas and liquid; to form a sealed heap. The sealed heap is irrigated with a leachant added inside the top of the heap, allowing the leachant to percolate through the heap and removing leachant at the base of the heap, either for recirculation or subsequent processing. Oxygen containing gas is added to the base of the sealed heap.