Pennsylvania Bluestone
Encyclopedia
Pennsylvania Bluestone is a layered sandstone
found only in the northeastern tier of Pennsylvania
, parts of northern New Jersey
and the southern tier of New York
. The quarried product has many uses, from cut dimensional stone used in patios, walkways and stair treads to architectural stone used in buildings. It is also used for wallstone, decorative boulders, natural steps and other landscape features. The name Pennsylvania Bluestone is due to its predominantly blue color and because the majority of stone is quarried in Pennsylvania; it can, however, appear in many other hues besides blue. It was formed over 360,000,000 years ago during the Devonian Period as large inland seas deposited sand in the Catskill
delta region. It is composed of feldspar
, sand, and mica
(among other minerals) and is clear of most organic residues.
The commercial refinishing process for bluestone cut slabs is called spalling. This process incorporates water and heat to reveal the natural layers of the stone as it was deposited originally. The cutting orientation must be almost exactly along the horizontal layers. The cut slab surface is soaked with water and heated rapidly with a wide nozzle propane torch
, breaking off chips of stone along their natural fault lines. The spalled slabs are called Pennsylvania River Rock or variations of this name depending on the market or origin of the stone.
If the initial deposit was made under slow moving water the ripples of the water action on the sand or mud will be revealed. This deposition process may be seen today at any ocean beach in shallow water or in a stream bed where conditions allow it to be observed.
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
found only in the northeastern tier of Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, parts of northern New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
and the southern tier of New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
. The quarried product has many uses, from cut dimensional stone used in patios, walkways and stair treads to architectural stone used in buildings. It is also used for wallstone, decorative boulders, natural steps and other landscape features. The name Pennsylvania Bluestone is due to its predominantly blue color and because the majority of stone is quarried in Pennsylvania; it can, however, appear in many other hues besides blue. It was formed over 360,000,000 years ago during the Devonian Period as large inland seas deposited sand in the Catskill
Catskill Mountains
The Catskill Mountains, an area in New York State northwest of New York City and southwest of Albany, are a mature dissected plateau, an uplifted region that was subsequently eroded into sharp relief. They are an eastward continuation, and the highest representation, of the Allegheny Plateau...
delta region. It is composed of feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
, sand, and mica
Mica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
(among other minerals) and is clear of most organic residues.
The commercial refinishing process for bluestone cut slabs is called spalling. This process incorporates water and heat to reveal the natural layers of the stone as it was deposited originally. The cutting orientation must be almost exactly along the horizontal layers. The cut slab surface is soaked with water and heated rapidly with a wide nozzle propane torch
Propane torch
A propane torch is a tool for burning the flammable gas propane . The maximum adiabatic flame temperature a propane torch can achieve with air is 2,268 kelvins...
, breaking off chips of stone along their natural fault lines. The spalled slabs are called Pennsylvania River Rock or variations of this name depending on the market or origin of the stone.
If the initial deposit was made under slow moving water the ripples of the water action on the sand or mud will be revealed. This deposition process may be seen today at any ocean beach in shallow water or in a stream bed where conditions allow it to be observed.
See also
- Bluestone in the United States
- FlagstoneFlagstoneFlagstone, is a generic flat stone, usually used for paving slabs or walkways, patios, fences and roofing. It may be used for memorials, headstones, facades and other constructions. The name derives from Middle English flagge meaning turf, perhaps from Old Norse flaga meaning slab.Flagstone is a...
- Opus 40Opus 40Opus 40 is a large environmental sculpture in Saugerties, New York, created by sculptor and quarryman Harvey Fite . It comprises a sprawling series of dry-stone ramps, pedestals and platforms covering of a bluestone quarry.-Overview:...