title: St. Clair Limestone
text: # St. Clair Limestone
  
  The St. Clair Limestone is a geologic formation in Arkansas, Indiana, Missouri, and Oklahoma. It preserves fossils dating back to the Silurian period. This high density, high magnesium dolomitic limestone was originally classified as a marble in Oklahoma due to the fact that it would hold a high polish, hence Marble City.
  
  ## Physical characteristics
  
  | | | Imperial | Metric |
  | - | - | - | - |
  | Absorption by weight | ASTM C97 | 0.5% | 0.5% |
  | Density | ASTM C97 | 168 lb/ft3 | 2 691.10 kg/m3 |
  | Compressive strength | ASTM C170 | 15 889Psi | 109.55MPa |
  | Modulus of rupture | ASTM C99 | 972Psi | 6.70MPa |
  