A mining report identifies the risk arising from any past, current and future underground and surface coal mining activity that may affect your home.
If your home is in an area where there has been mining or brine extraction then your purchasers solicitors is likely to ask for a coal mining report so by providing on in your you can save time. The coal authority provide a list of areas where they would recommend a mining report at http://www.coal.gov.uk/services/miningreports/gazetteer/englandwalesgazetteer.cfm