bluestone

Bluestone is a common, non-technical name applied to several different blue-gray stones used in masonry and paving. It is not a single mineral or rock type, but a regional term that describes stones with a similar color in the finished work.

In North America, bluestone most often refers to a sandstone or siltstone quarried in the northeastern United States and neighboring areas. The material is typically cut into flagstones or dimension stone and used for sidewalks, flooring, wall veneers, and exterior paving. The Catskill Formation, for example, yields a dense, blue-gray stone that has long been marketed as bluestone.

In the United Kingdom and Ireland, the word commonly denotes hard, dark blue-gray rocks such as basalt or dolerite used for paving and construction. The term is also associated with the bluestones of Stonehenge, a prehistoric set of stones from western Britain that include dolerite, rhyolite, and other rock types transported to the site during prehistory.

In Australia, bluestone usually refers to a dark basalt or basalt-like stone used in urban architecture, fencing, and paving, particularly in Victoria and surrounding regions. It is prized for its durability and distinctive color when dry or polished.

Physical properties vary with rock type but the common feature is a blue- or blue-gray appearance. Durability and weather resistance make bluestone suitable for exterior and heavy-traffic applications, though care and sealing requirements depend on the specific stone. Because the term covers multiple rocks, precise identification commonly requires quarry information or petrographic analysis.