Large quantities of material covering a fossil, known as the overburden, may be loose gravel, sediments or rockfall. It can be removed with a spade or perhaps a pick-axe. (Professionals sometimes use road-drills, jack- hammers, construction diggers or even explosives, but these are beyond most part-timers.) Then hammer and chisels can be employed. Keep an eye on the rock fragments as they are removed. If the fossil is well embedded in matrix, try to assess its overall size and position, and work around this, leaving plenty of room for error. Try a trial few blows on a rock of the same type which does 'not contain a fossil, to see how the rock reacts and splits or shatters. Do not chip or scratch the fossil itself, which could spoil its appearance and considerably reduce its scientific value.