Concrete is a widely used material in which sand, gravel, limestone or chalk, marl, and gypsum are the main ingredients. Demolished concrete structures are commonly reused as fill for other construction projects. Some industrial diamond is recycled from drill bits and cutting tools. There is a continuous search for new deposits of industrial rocks and minerals to replace deposits being depleted. A problem faced by the producers of some nonmetallics is that large tonnages are required by users, coupled with low market prices per unit.
Low prices cause transportation costs to be a critical factor.
In addition, expansion of suburbs around major markets and increasing environmental constraints have forced many operators to move to more distant sites, thereby increasing transportation costs and prices paid by consumers.