Rock
Brownstone
Brownstone
The stone that named New York's famous row houses: a brown sandstone easy to cut and carve, but prone to flaking over time.
Also known as: Connecticut River brownstone · Portland brownstone · Hummelstown brownstone · Freestone
- Popularly: Natural stone (building and decor)
In short
Brownstone is a brown Triassic–Jurassic sandstone quarried in the eastern United States, and it was a much-loved building stone in the 19th century. Its best-known sources are the quarries of Portland, Connecticut, the Passaic Formation of northern New Jersey and Hummelstown, Pennsylvania. In the US and Canada the word “brownstone” also means a townhouse clad in this or a similar-looking material; New York neighbourhoods such as Brooklyn and Harlem are known for them.
Photos
How does it form?
Brownstone formed around the end of the Triassic and the start of the Jurassic, in rift basins that opened in eastern North America as the supercontinent Pangea began to break apart. Sand and mud from the Appalachian mountains to the west settled in these basins, in shallow lakes, dry plains and alluvial fans. Over time the sand grains were compacted and cemented into sandstone.
The Passaic Formation of northern New Jersey is a product of these basins: it is about 219–201.7 million years old and up to 4 kilometres thick at the deepest part of the basin. Its reddish colour points to sediments laid down in a dry climate.
What is it used for?
- Row houses: In the 19th century thousands of New York townhouses were faced with brownstone, in Brooklyn neighbourhoods such as Park Slope, Fort Greene and Bedford-Stuyvesant and in Manhattan’s Harlem and Upper West Side. The Victorian brownstone homes of Boston’s Back Bay are also famous.
- Public buildings: Portland stone went into landmark buildings in Chicago, Boston, New York, Philadelphia, Washington, Baltimore, New Haven and Hartford. Hummelstown stone faces government buildings in several states.
- Gravestones: In colonial times, gravestone carvers in southern New England and the Mid-Atlantic used brownstone widely.
- Country buildings: Early Quaker settlers in Pennsylvania built their mills and mill houses of it.
Where is it found?
The main sources of brownstone are the quarries in and around Portland, Connecticut, the Passaic Formation of northern New Jersey and Hummelstown near Harrisburg, Pennsylvania. Brownstone quarries were also worked in the 19th century on the Apostle Islands of Wisconsin. The Portland quarries opened in 1690; today they are flooded and used as a nature and adventure park.
What determines its value?
Its value lay in being easy to quarry and carve and in its warm brown colour. But the same qualities make it weak against the weather: brownstone façades crumble over time and need repair. Today new stone is cut mainly for restoring historic buildings, on a small scale, from quarries whose colour and texture match.
This information is educational, not buying, selling or investment advice. Value varies enormously with quality and treatment.
How to recognise it
- 1
A chocolate- or rust-brown stone with a sandy grain.
- 2
On old buildings its surface often looks crumbled, flaked or rounded.
- 3
Being a sandstone, its grains can be seen with a hand lens, and rubbing the surface may shed sand.
Myths and misconceptions
MythBrownstone is a very durable stone.
FactWhat made brownstone popular was how easily it could be cut and carved, but that same quality makes it weak against the weather. Brownstone façades and gravestones wear far faster than slate or schist stones of the same period.
Did you know?
A typical feature of New York brownstones is the stoop, a steep staircase from the street up to an entrance almost at second-floor level. It was seen as hygienic at a time when the streets were foul with animal waste.
Proceeds from the Portland quarries in Connecticut were deeded to Wesleyan University from 1833 to 1884, and many of its buildings were built of the stone.
Colonial gravestone carvers in New England loved brownstone because it was easy to carve. In the early 1800s it gradually gave way to marble.
Where is it found?
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- Portland Brownstone Quarries, Portland, Connecticut, USA · Type localityThe main source of “Connecticut River brownstone”. Quarrying began in 1690, and at its peak more than 1,500 workers were employed. A National Historic Landmark since 2000; since 1994 stone is cut here only on a small scale, for restoration.
- Hummelstown, Pennsylvania, USA · Major depositThe Hummelstown Quarry, the largest brownstone supplier on the US East Coast; its stone faces government buildings in several states.
- Basswood Island, Apostle Islands, Wisconsin, USA · Historic sourceA quarry worked from 1868 into the 1890s; its stone went into the first Milwaukee County Courthouse in the 1860s.
Locations are approximate to protect sites. Red dots mark places in Türkiye. Open in the big map →
Frequently asked questions
What is brownstone?
Brownstone is a brown Triassic–Jurassic sandstone quarried in the eastern United States, and it was a much-loved building stone in the 19th century. Its best-known sources are the quarries of Portland, Connecticut, the Passaic Formation of northern New Jersey and Hummelstown, Pennsylvania. In the US and Canada the word “brownstone” also means a townhouse clad in this or a similar-looking material; New York neighbourhoods such as Brooklyn and Harlem are known for them.
Is every “brownstone” house really built of this stone?
No. “Brownstone” has come to mean almost any townhouse of a certain period. Some Brooklyn “brownstones” are actually brick with concrete cladding that imitates stone, and in others only the stoop is brownstone.
What is brownstone used for?
Row houses: In the 19th century thousands of New York townhouses were faced with brownstone, in Brooklyn neighbourhoods such as Park Slope, Fort Greene and Bedford-Stuyvesant and in Manhattan's Harlem and Upper West Side. The Victorian brownstone homes of Boston's Back Bay are also famous. Public buildings: Portland stone went into landmark buildings in Chicago, Boston, New York, Philadelphia, Washington, Baltimore, New Haven and Hartford. Hummelstown stone faces government buildings in several states.
How hard is brownstone?
It has a hardness of 6–7 on the Mohs scale. It can scratch glass; a steel knife scratches it only with difficulty. Its specific gravity is 2.2–2.8 g/cm³.
Where is brownstone found?
Its best-known localities: Portland Brownstone Quarries, Portland, Connecticut, USA; Hummelstown, Pennsylvania, USA; Basswood Island, Apostle Islands, Wisconsin, USA.
How can you tell if brownstone is real?
A chocolate- or rust-brown stone with a sandy grain. On old buildings its surface often looks crumbled, flaked or rounded. Being a sandstone, its grains can be seen with a hand lens, and rubbing the surface may shed sand.
Is brownstone valuable?
On the “street to diamond” value ladder it sits on step 3 of nine: Building and industrial stone. Its value lay in being easy to quarry and carve and in its warm brown colour. But the same qualities make it weak against the weather: brownstone façades crumble over time and need repair. Today new stone is cut mainly for restoring historic buildings, on a small scale, from quarries whose colour and texture match.
Sources
- Brownstone · Wikipedia
- Portland Brownstone Quarries · Wikipedia
- Hummelstown, Pennsylvania · Wikipedia
- Basswood Island · Wikipedia
- Passaic Formation · Wikipedia
- Sandstone · Encyclopaedia Britannica
- Common rock densities · chemeurope.com (from Wikipedia, GFDL)
External links
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