blue metal
Hard dark stone crushed into small pieces used in surfacing roads, for ballast in…Hard dark stone crushed into small pieces used in surfacing roads, for ballast in railway tracks, etc; gravel; road metal.
Meaning
1 senses(Australia, New Zealand, uncountable)Hard dark stone crushed into small pieces used in surfacing roads, for ballast in railway tracks, etc; gravel; road metal.
Lessons for this word
1 lessons- A1Countable and uncountable nouns — Because it can be uncountable