Types of Slate: Pennsylvania Black Slate (Bangor and Pen Argyl)

Updated: Jun 27

There are many types of Pennsylvania Black Slate, but in this segment we are going to focus on the ones that came out of the Lehigh-Northhampton district that include the Bangor and Pen Argyl quarries.

The slate production here hit its peak in 1903 when it

was one of the largest slate producing regions in the world.


Pennsylvania Black slate have a black or dark grey color, but when first quarried tend to have a blue-black appearance.


The Pennsylvania Black slate is a softer slate, designated as an S2 slate with a life span of 50-125 years.


New Pennsylvania Black Slate


As these slate age they can develop a light gray border around the bottom that is due to the calcium in the slate coming to the surface. Some of these slate also develop a light brown and flaky appearance that comes from the iron in the slate.


The downfall to these slate is that they do have a somewhat shorter lifespan and as they get older they become softer and crumble. Although Pennsylvania black slate do have a shorter lifespan it is still much greater than any shingle roof. If you have Pennsylvania black slate on your roof please be sure to call us and we can inspect it to determine its condition and make any necessary repairs.

Older Pennsylvania Black slate with Iron coming

to the surface


Be sure to stay tuned as we cover some of the much harder and longer lasting types of Pennsylvania Black slate, such as Chapman and Peach Bottom in our next segment!