The Mining (Strategic Prospectivity Zones) Act 1993 recognises the high mineral prospectivity of many areas of Tasmania. Within the Strategic Prospectivity Zones (SPZ) there are restrictions on changes of the status of parcels of Crown Land. The status of Crown land parcels <500 ha in size can only be changed with the agreement of the Director of Mines; those of > 500 ha in size cannot be changed without the approval of both houses of parliament. Should a change in land status made by the State have the effect of revoking a mining lease or an exploration licence, the tenement holder is entitled to compensation. The State is, however, not responsible for actions of the Australian Government which may preclude exploration or mining. activity, such as the nomination of parcels of land for World Heritage status. Changes in status of land can also be made in extreme circumstances, for example if a species of flora or fauna was to become rare, vulnerable or endangered as a result of mining activity, or where an area having cultural or natural heritage value could suffer substantial effects as a result of mining operations. In these cases the Crown may, after a recommendation from the Resource Planning and Development Commission and some Ministers, change the status of that piece of land, and compensation is payable for this action.