About Pennsylvania Bluestone

Stones have stories.


Side view of PA Bluestone standing up on pallets.

Irregular shapes of natural cleft Pennsylvania Bluestone standing up on pallets. (Credit: Buddingco)

These natural stones in our masonry yard (above) are known in general as flagstone or specifically as bluestone. Pennsylvania or PA Bluestone is quarried in northeastern Pennsylvania, the Catskills of New York state, and areas in northern New Jersey. The standups (because they are standing up on pallets) are irregularly-shaped pieces with natural cleft surfaces. That is, the tops are somewhat uneven rather than uniformly smooth, resulting from excavated rock that naturally breaks and splits along its seams. These splits create slabs of flat stone aka flags (or flagstone) used for paving.

Large slab of PA Bluestone.

Muliti-color PA Bluestone (Credit: BuddingCo)

As its name suggests, PA Bluestone comes in bluish hues. Other colors are gray, green, brown, tan, lilac, rust, and full color. Like snowflakes no one stone is like any other. According to the Pennsylvania Bluestone Association this material originated 360,000,000 years ago when seas covered the land leaving sand behind. Thus, the term sandstone–bluestone’s main ingredient. Over time residual water deposits of clay and minerals variegated the rock.

A large slab (left) exemplifies the variance in full color PA Bluestone. Zooming in microscopically (below) heightens the rippling effect of natural clef texture and exposes multiple tints from iron ore rust and more. Isn’t Mother Nature’s palette absolutely fabulous? Who knew that many paths we have walked and terraces we have trod upon consisted of such exquisiteness.

Close up of full color PA Bluestone.

Zooming in on details of full color PA Bluestone (Credit: BuddingCo).

Exploring further, I ran across a collection of historic photos from the Pennsylvania Geological Society Library. This image (below) taken in 1922 reveals a sandstone quarry in Pike County. See how the layers of bluestone built up over time? I wonder who else besides the boy (lower right) has seen this spectacular sight? Such are this week’s masonry musings.

Old picture of Sandstone Quarry located in Pike County Pennsylvania in 1922.

Sandstone Quarry, Pike County, Pennsylvania (Credit: Ralph W. Stone, 1922, Public Domain, PA Geological Survey)