Philadelphia Reflections

The musings of a physician who has served the community for over six decades

Related Topics

Historical Preservation
The 20% federal tax credit for historic preservation is said to have been the special pet of Senator Lugar of Indiana. Much of the recent transformation of Philadelphia's downtown is attributed to this incentive.

Architecture in Philadelphia
Originating in a limitless forest, wooden structures became a "Red City" of brick after a few fires. Then a succession of gifted architects shaped the city as Greek Revival, then French. Modern architecture now responds as much to population sociology as artistic genius. Take a look at the current "green building" movement.

Customs, Culture and Traditions (2)

Chester County, Pennsylvania
Chester was an original county of Pennsylvania, one of the largest until Dauphin, Lancaster and Delaware counties were split off. Because the boundaries mainly did not follow rivers or other natural dividers, translating verbal boundaries into actual lines was highly contentious.

Serpentine Rock From Serpentine Barrens


Even in pre-revolutionary Colonial days, it was recognized that patchy areas of Chester and Lancaster counties were covered with twenty-foot stunted evergreens instead of two-hundred-foot oaks. They were "barrens", resembling the pine barrens of central New Jersey. In time, these barrens were particularized as Serpentine barrens, out of a recognition that this stunting of vegetation was somehow associated with greenish stone in the bedrock. So, the serpentine barrens in time became serpentine rock quarries, but they seem somehow less barren now that surrounding deciduous forests have been cut down to make nice farmland. The greenish stone was a novelty, especially because it was usually (but not invariably) soft sandstone and easy to quarry, and the bedrock was only an inch or so under the topsoil, or even appeared on the ground surface as outcropping. These qualities made serpentine a popular building material, but in retrospect, it should have been more apparent that sandstone crumbles easily, and what can stunt tree growth probably wasn't very good for you.

Serpentine Rock

Well, the green color comes from chromium salts. Sometimes the greenish color is diffused throughout the volcanic rock, but more commonly concentrated in green veins "snaking" through sandstone. Diffuse is better for building because the greenish intrusions create fracture lines in response to acid rain. In modern times, we mostly think of chromium as imparting a shiny look to plated auto bumpers. Some automaker was once quoted as saying he sold more cars using $10 worth of chrome than with $100 worth of engineering. That's metallic chrome because central to the definition of a metal is that it looks shiny. Even high school chemistry scholars can tell you it is a "salt" of chromium, the chromic ion, which imparts a greenish tinge when dissolved in water. So, chromic salts dissolved in the local water are what dwarf the vegetation of a serpentine barren, not chromate (which is yellow), and not metallic chromium (as in auto trim). So, although one might suppose otherwise, a few years ago when local builders started up modern quarries of the serpentine rock, the environmentalists of Chester County were up in arms. Demonstrations were held, editorials are written, politicians hectored. The Serpentine Barrens was a local treasure, requiring legal protection; protective ordinances were demanded.

Building construction with Serpentine Rock

Although building construction with the serpentine rock had a considerable flurry in the late 19th Century, the crumbly nature of sandstone caused the disappearance of all but a few examples. A building in boathouse row on the Schuylkill, a pre-revolutionary house on the Brandywine battlefield, College Hall on the campus of the University of Pennsylvania, pretty much comprise the notable surviving examples. But in a certain way, the Serpentine buildings do sort of define Victorian Philadelphia.

California is not within the intended scope of Philadelphia Reflections. However, it probably should be mentioned that Serpentinite is the official California rock, as would be natural for a substance which composes about 2000 square miles of its bedrock. It's green in color, but has high magnesium content, and seems to originate with the grinding of tectonic plates as they throw up mountain ranges, with attendant earthquakes. California also has serpentine barrens, but local geologists blame that harmful vegetation effect on magnesium competing with soil calcium (rather than the less notable chromic ions in West Coast serpentine). We're getting into some pretty fine distinctions, here. Pennsylvanians will probably be content to know we found ours first, that it had a flurry in Victorian architecture, and it's just a bit quaint. And, that it doesn't pose a significant risk for asbestos poisoning. A California geologist, in defending their state rock honor, recently proclaimed there was a greater statistical risk of dying from their state animal (the grizzly bear) than from their state rock.


The Pine Barrens: John McPhee: ISBN-13: 978-0374514426 Amazon

Originally published: Tuesday, June 29, 2010; most-recently modified: Wednesday, June 05, 2019

Here in Chicago's far southside in the Pullman Community, we have the Greenstone Church which is built of Pennsylvania Serpentine Stone. The church was designed by architect Solon S Beaman architect of George Pullman's utopian worker's town and factory. Further information can be found at Greenstone Church was built in 1882 and is fine shape thanks to funding and volunteer hours by the Historic Preservation Community's residents a number of years ago. Currently, Pullman recently became part of the National Park Service with our factory administration and clock tower becoming a National Monument. Thank you. CJ Martello, 11403 South Saint Lawrence Avenue, Chicago, Illinois 606028-5113. tel: 773-701-6756.
Posted by: CJ Martello   |   Oct 19, 2015 12:51 AM
The green stone house at the corner of Rts 202/322 and 926 (Street Road) is still there, as I drove by it last week (July 2015). Many years ago as a leader in the Indian Guides organization, I went with a group to the serpentine rock quarry near West Chester.
Posted by: Gpop   |   Aug 6, 2015 1:05 PM
There is or was a green stone house, which I assumed was serpentine, at the corner of Rts 202/322 and 926 (Street Road) just south of West Chester. I haven't gone that way in years-- live in MD now-- but I think it's still there in MapQuest satellite photos, on the NW corner of the intersection. If I'm wrong about the intersection being 926, it was another one close by on 202/322. Wish I'd taken a good photo when I was in the area.
Posted by: Rhea   |   Mar 12, 2014 10:09 PM
I owned a house in West Chester @ 341 Hannum Ave which is made of Serpentine Stone. I removed the stucco, cleaned and repointed the stonework about 1990. The former owner said the house was built in 1814 and based on an Elfreth's Alley design. There are about 8 houses in a row all with the same design and all made of Serpentine. The quarry for the stone was supposedly about 2 miles south of the college on New Street where there is indeed a small quarry.
Posted by: corypenman   |   Jun 21, 2013 10:15 AM
I was surprised and pleased to that you included two photos of my house in your article. In 1729 William Brinton opened a quarry about a mile down the road, and in 1730 James Townsend built this house. Some types of serpentine may be crumbly, but at least the top layers of Brinton's Quarry can stand the test of time. Two hundred eighty three years and still standing.
Posted by: alan   |   Mar 22, 2013 5:08 PM
The former "Old Main" building on the campus of the West Chester State "Normal School", now the West Chester State University of Pennsylvania, was built entirely of Serrpentine, as were many other lesser buildings on the campus. To attest to the unstable qualities of the stone as a building material, the crumbling old building was razed some years ago, and replaced by a modern construct. In defference to historical significance, the original serpentine entry arch still stands in front of the new building. Very nicely done.
Posted by: David   |   Jul 24, 2012 1:15 PM
The serpentine facade displayed in the closeup photograph is an excellent example.
Posted by: J.Gordon   |   Aug 9, 2010 5:13 PM
which is the serpentine building at u of p?
Posted by: bzpaul   |   Jul 7, 2010 12:32 PM
It is the Chromic or Cr+++ ion which in concentrated solution in water is spruce green. Chromium oxide, Cr2O3, is also green, hence the green color of Serpentine rock. K2Cr2O7, potassium dichromate, is orange and K2CrO4, potassium chromate, is yellow.
Posted by: J.Gordon   |   Jun 30, 2010 11:02 PM