Wood – Very soft material. The oldest monuments in this area were wood. Monuments made of wood didn't last long.
Sandstone – Soft material. Old monuments made of sandstone sometimes have larg holes of wear.
Marble – Very old marble headstones look chalky and rough from years of exsposure to weather. Inscriptions can be hard to read due to wear.
Granite – Granite is very hard and more durable than the others.
Zink – A fade beginning in the 1870s, inexpensive monuments made of zinc.
Called "White Bronze" to make them more appealing to customers. Individual pieces ordered from a catalog and then bolted together on site.
Left exposed to the elements the monuments rapidly form a tough and very durable skin of zinc carbonate that protects the underlying metal.
The zinc carbonate is what gives the monuments their characteristic bluish gray color.