Tuesday, March 2, 2010

What Rocks Can Make A Gravestone

Durable and beautiful stone tablets await carving.


Since the ancient Egyptians laid pharaohs to rest in carved stone sarcophagi and built pyramids to mark the rulers' resting places, people have built stone monuments to commemorate the deceased. Durable carved stone grave markers convey information across hundreds or even thousands of years, granting a form of immortality to a loved one's name or likeness. Stonemasons add even more meaning to a gravestone with engraved messages or bas-relief elements.


Marble


Even on overcast days, white marble gleams.


Softer limestone or calcite transforms under heat and pressure to become metamorphic marble. One of the most famous monuments to a departed loved one, the Taj Mahal, consists of white marble. The stone comes in other colors, but sculptors and stonemasons prize white marble for the slight translucency that makes the stone gleam in the light. Darker tones like gray, green or black marble may suit the somber purpose of gravestones as well. Marble combines durability with softness, allowing stone workers to incise it easily with names and dates that will remain legible for centuries.


Granite


Engravings on dark granite can become quite intricate.


The igneous stone granite consists of other minerals such as quartz, feldspar or mica fused together, but still visible as discrete components. Its characteristic mottled appearance comes in a wide variety of hues from pale gray to pink to black. Some granites look more uniform in color, while others are more variegated. Granite's chief virtue as a gravestone is its durability; granite takes centuries to show wear. Early stonemasons had more difficulty working with the rock, but modern artisans' tools can engrave it with relative ease. Laser etching allows granite tombstones to bear complex images, even portraits of a loved one.


Basalt


Columnar basalt naturally has a monumental appearance.


Dark, heavy and fine-grained, basalt's monolithic quality lends itself to large monuments. Artisans crafted some of the moai on Easter Island from basalt; the great stone heads are not gravestones, but they honor departed ancestors. Because of its uniform dark hue, basalt gravestones may bear gilded or painted text to make the words easier to read. Stonemasons can polish this igneous rock to a high shine or to a softer satiny finish that more closely resembles the surface of ancient basalt statuary.


Sandstone


Carved shapes in sandstone have rounded edges, not crisp forms.


Modern stone workers rarely use friable sandstone for gravestones, but earlier artisans frequently used it for its availability and simplicity to shape. Sandstone is not a single rock, but a sedimentary composite of a harder mineral in small grains, usually quartz, in a softer matrix of stone. Its structure makes it easy to work, but hard to carve with precision; text on sandstone markers has softer edges than that on igneous or metamorphic rock. Sandstone grave markers in humid climates may become illegible after less than a century.


Limestone


Limestone pits and scars in the the presence of acid rain.


This calcium-rich sedimentary precursor to marble looks handsome and weathers well in arid climates, but erodes quickly in acidic environments. In climates prone to acid rain, limestone markers lose their legibility within decades. Depending on the type of limestone and how it formed, extremes of temperature can cause the stone to flake away in sheets. Older limestone tombs and markers reflect the stone's availability and workability. Although an acidic or humid environment will reduce limestone to powder within a few centuries, it remains a beautiful and durable option for interior markers such as those in mausoleums and cathedrals.







Tags: white marble, acid rain, carved stone, grave markers, stone workers