blue metal
Noun
Meaning
blue metal (uncountable)
(Australia, New Zealand) Hard dark stone crushed into small pieces used in surfacing roads, for ballast in railway tracks, etc; gravel; road metal.
Noun
blue metal (uncountable)
(Australia, New Zealand) Hard dark stone crushed into small pieces used in surfacing roads, for ballast in railway tracks, etc; gravel; road metal.