Concrete Color Guide (pdf document download)
Material (driveway gravel, sand, topsoil, fill materials)
For 1.5 inch washed landscaping rock, use the following:
1 square foot of cover = 20lbs. of rock OR 1 ton of rock will cover 100 square feet.
The most common materials, like driveway gravel and basecourse, figure out to 1.5 tons per cubic yard. Materials like washed sand and chips come out to 1.3 tons per cubic yard.