Sunday, October 3, 2010

Identifying Major StoneTypes

This information was taken from The Association of Gravestone Studies. It has been very helpful to me so I though I would share it.

  • Igneous rock with visible grain, primarily quartz and feldspar
  • Speckled appearance with sparkly mica and dull black flecks
  • Extremely hard rock that is difficult to carve by hand
  • Grays, pinks in a wide range of colors
  • Commercial granites include gneiss and other rocks not strictly granite
  • Exhibits a full range of grain sizes with uniform surface patterns
  • Granular with no discernable bedding planes
  • Often used for monuments and tombs
  • Soft, sedimentary rock primarily composed of calcite
  • Fossils may be recognizable and are the most diagnostic trait
  • Tan, buff or gray colored that darkens with age
  • Matte surface almost never polished
  • Somewhat rough texture, rarely “sugars” like marble
  • No marked veining like marble
  • No definite layers or bedding planes like sandstone
  • No sparkly mica grains like granite
  • Often gets gypsum crusts
  • Hard, dense crystalline or granular metamorphic limestone
  • White when new or in new breaks, but older marbles may appear gray from soiling
  • Capable of taking a high polish, yellows with age
  • May have veins of gray or gold
  • Commercial marble is any lime carbonate capable of taking a polish, could include limestone and many colors
  • Tennessee marble is medium-grained similar to limestone in texture with a pink cast
  • Georgia marble is very large-grained, somewhat gray in color
  • Predominant stone for gravestones in the 19th century
  • Many early marbles are eroded and “sugaring”
  • Sedimentary rock composed of cemented sand grains – “bedding planes”
  • Red and brown (Brownstone) in color, can be gray, tan or blue (Bluestone)
  • Fine-grained stone with sand grains
  • Often flakes and delaminates
  • Metamorphosed shale, hard and brittle
  • Usually black, gray or blue
  • Sometimes fades with time
  • Extremely smooth, fine-grained stone with even bedding planes usually running parallel with the stone’s face
  • Holds carving very well, inscriptions usually very clear
  • Uniform surface appearance
  • Gravestones tend to be thin and simple in shape, generally not more than six inches
  • Metamorphic rock
  • Largely composed of the mineral talc and is rich in magnesium
  • Easily carved and darkens over age
  • Smooth to the touch
  • Used in 19th century, commonly for slot and tab tombs in Georgia
  • White, gray, greenish gray, pale green -- commonly discolored in reddish or brownish hues and mottled

1 comment: