Behind the brownstone veneer

This partially demolished wall at the General Theological Seminary in Chelsea is an excellent illustration of how brownstone structures were made. 

Brownstone is essentially sandstone, a form of sedimentary rock composed of layers of sand. The rich brown color of much of the material seen in buildings around town comes from the presence of iron ore. Widely used in 19^th century New York (it was cheaper than other stones and readily available in New Jersey and Connecticut) brownstone was primarily used as a veneer over brick walls. My first photo illustrates this, with a layer of brownstone blocks about 4 inches thick cemented to brick. The close-up shot of a broken brownstone block shows how the sandstone is composed of layers.