Gravestones (a.k.a. headstones / tombstones) in modern American cemeteries are usually made of "granite" - a term in the retail trade for any hard stone that will take a fine polish. Geologically, some are granites and some are not. In the 1800s, many gravestones were made of marble, a crystalline-textured metamorphic rock composed of calcite (calcium carbonate, CaCO3). Rainwater is naturally acidic (slightly) from carbonic acid - H2CO3. Over time, marble will slowly dissolve in rainwater. Older marble gravestones often have poorly legible or non-readable carvings.
Seen here is a closeup of an 1800s gravestone showing discoloration of the marble. Small patches of living lichen are present.
Locality: St. John's Lutheran Church Cemetery, northern side of Holston Road, Wytheville, southwestern Virginia, USA
Loading contexts...
