The term road metal refers to the crushed rock used for road beds and surfaces, foundations and railway embankments, among other things. The use of road metal dates back to antiquity, but was more recently pioneered by John Loudon McAdam in the late 18th century. The word metal comes from the Latin metallum and the Greek metallon meaning "mine, quarry, ore, metal". The reference to crushed rock therefore becomes more apparent. The term is relatively rarely used today, with 'gravel' being more typically used and understood. One of the places where it is still in common usage is New Zealand.
