NHT: White Bronze…why’s that monument different? EarthCache

This earthcache will introduce you to a rare type of cemetery monument and compare it to other nearby ones.  It is located in Norfolk's Historic Triangle.  

In the mid-1800s the Industrial Revolution was at full speed.  M. A. Richardson and C. J. Willard came up with a new way to capitalize on the new factory system and the Victorian mourning traditions of the time.  In 1873, Richardson began inventing monuments made of zinc.  Unable to get enough capital, he sold out and the Monumental Bronze Company started officially in 1879.  The idea was simple.  Prefabricate most of the monument, then just fill in names and dates and other personalization to get the customers what they wanted.  They were easier to construct than traditional stone monuments, as well as, cheaper to produce and ship.  Sales hit their peak in the 1880s.  Some people however, thought the monuments cheap imitations and banned them.  By WWI, production was shut down as all zinc was needed for the war effort. 

To construct the monument a mold was constructed just like for granite or marble monuments.  After the mold was finished, the zinc was heated beyond its melting point to ensure a better fuse then traditional soldering.  The monument was then sandblasted and chemically oxidized to resemble granite and receive its bluish cast.  When exposed to the carbon dioxide (CO₂ ) in the atmosphere, zinc naturally covers itself in a layer of zinc carbonate  Zn₅(OH)₆(CO₃)_2.  This prevents further reaction with air and water. Strong acids, or even acid rain, however will still trigger a chemical reaction.

One problem that cemeteries has is weathering of stones or the breakdown of rock in situ, that is without moving, and should not to be confused with erosion.   Traditional stones are made of granite or marble.  Marble tends to be a very soft stone and weathers quickly.  Granite tends to take a while longer, but still fades over time.  Weathering is caused by the elements like rain and ice, or even biological means like lichens and ivy.  Weathering varies by location based on a host of variables, but a study in Yorkshire, England found that the average marble stone became difficult to read after 70-80 years while igneous rocks, like granite, lasted up to 100-150 years in comparison. 

Spalling is another by product of weathering.  In spalling, the layers of rock begin to separate and flake off.  In some cases, these fractures cause other minerals to leak out and form small stalactite like structures on larger monuments. 

There are two white bronze monuments within a few feet of the given coordinates.  One is for the family named Williams.  The other is the Benson family’s.  Take a close look at them and then at some of the other nearby more traditional monuments. 

To get credit for this earthcache, answer the following.  Please email the CO.  Logs will posted answers will be deleted.  Sorry! 

1.  Compare the weathering of the white bronze monuments to those around it.  In terms of readability and resistance to lichens and discolorations, which markers are holding up the best?  Would you estimate that the Yorkshire study is valid in the Norfolk, Virginia area with stones lasting about 100 years for readability? 
2. Take a close look at the details on the white bronze monuments.  How long do you think that these monuments might last in comparison?
3. If you look at the Benson monument, the angel has some spots on her wings and head almost like spalling.  Based on the protection provided by the zinc carbonate, what do you think probably caused these spots?
4. The monument itself is hollow.  It is said that is some cemeteries, the gardeners would hide their tools in them.  Later, outlaws and bootleggers used their hollow structure to their advantage also.  Look closely at the base of the larger Benson monument.  Do you see any issues caused by this construction?  If the monument was even larger, what do you think might happen?

To read the results of the Yorkshire study and learn how to do your own weathering study in a cemetery look at:  http://www.wyorksgeologytrust.org/misc/Teaching%20weathering%20in%20West%20Yorkshire.pdf

This cache was placed with permission of the Norfolk Society for Cemetery Conservation.

Please cache only between the hours of 6 a.m. and 7 p.m.