Physically, these are recrystallized, Hard, Compact, fine to very fine grained metamorphosed rocks capable of taking shining polish.
|Hardness||3 to 4 on Moh's Scale|
|Density||2.55 to 2.7 Kg/cm3|
|Compressive Strength||70 to 140 N/mm2|
|Modulus of Rupture||12 to 18 N/mm2|
|Water Absorption||Less than 0.5% (except Rainforest Green/Brown with 2-3%)|
Chemically, they are crystalline rocks composed predominantly of calcite, dolomite or serpentine minerals. The other minor constituents vary from origin to origin.
|Silica (SiO2)||3-30% (varies with variety)|
|MgO||20 to 25%|
|FeO + Fe2O3||1-3%|
|Loss On Ignition (LOI)||20-45%|