cinder quarry
A site extracting naturally occurring volcanic cinders in bulk for uses such as surfacing, mulch, or material mixtures.
A cinder quarry is a place where naturally occurring pyroclastic cinders are extracted from the ground, normally in areas with present or past volcanic activity. Cinders are used in roads and pathways for added traction, and are often used as a decorative mulch in landscaped areas. They are very light and porous, and are not generally suitable for construction except as an ingredient mixed with other construction materials.
The cinders come from natural pyroclastic deposits. Cinders produced by industrial fuel burning are not the volcanic material described by this quarry use.
Their light, porous form suits loose surfacing, decorative mulch, and use as an ingredient in mixtures. The definition concerns extraction rather than a plant manufacturing finished construction products.