What Is Pennsylvania Bluestone?

Geology of Pennsylvania Bluestone

• Pennsylvania Bluestone is a type of sandstone made up of compressed layers of sand from the bottom of a series of tidal flats that covered northeastern Pennsylvania over 400 million years ago. Uniquely, this area featured fast moving, shallow water that dropped an array of sediment in a long path, creating the unique look of the stone. As the sand and various debris and organisms fossilized and hardened, it formed a unique type of stone now called Pennsylvania Bluestone.

Uses of Pennsylvania Bluestone

• There are two different levels of quality, or grades, of Pennsylvania Bluestone. Builders use Architectural grade sandstone for steps, door fixtures, counters and tables, while flagstone is useful for walkways and patios. While relatively rare, Pennsylvania Bluestone's strength and durability make it prized for construction and the ease of separating it into giant, workable slabs made it especially useful compared to other stone.

Production of Pennsylvania Bluestone

• Once workers wielding diamond-tipped saws hew those giant blocks of Pennsylvania Bluestone, they are transported into "saw shops" where they're shaped and cut down to size for various architectural uses. Production of Pennsylvania Bluestone requires permits from a variety of federal and Pennsylvania agencies and requires careful attention to environmental issues such as runoff and water quality.

Where To See Pennsylvania Bluestone

• In Pennsylvania itself, buildings or structures featuring Pennsylvania Bluestone include the Morris Arboretum at the University of Pennsylvania, Independence Mall, the Susquehanna County Courthouse, and the Staracca Viaduct in Lanesboro, PA. The famous "Castle" in Hawley PA is one of the largest Bluestone buildings in the country. Around the United States, Bluestone buildings include The Peace Bell Garden at the United Nation Headquarters in New York, as well as the walkways around the building. Princeton University features walkways and buildings in Pennsylvania Bluestone, as does the Riverwalk in Pittsburgh, the Doris Duke Center and Sarah P. Duke Gardens at Duke University, and the Rose Garden terrace at the White House.