Geology

Basic geology helps identify stone and its properties

Four types of rock:

  • SEDMINTARY: sand, gravel and organic material compacted and cimented
    • observable layers
    • hardness: soft
    • does not retain polish
    • sandstone: silica (sand, quartz)
    • limestone: fossils of algae, shells, bones (no silica)
    • conglomerate: mud and gravel
  • VOLCANIC: extrusive magma
    • lava cooled quickly when exposed to air or water
    • small crystals
    • can be polished
  • PLUTONIC: intrusive magma:
    • magma that cooled slowly in the Earth’s interior
    • large crystals, or complete crystalization
    • uniform granular texture
    • can be polished
    • contains silica (quartz), mica and feldspar
  • METAMORPHIC:
    • existing rock transformed by heat and pressure
    • observable folding or distorted strata
    • ex. marble (transformed sedimentary)
    • ex. gneiss (transformed granite)

Québec geoscientific database

  • SIGÉOM 150 years of data from mining and mapping surveys

A basic knowledge of geology means you don't use limestone for foot traffic areas or wet areas such as countertops, and you don’t use iron tools on granite (use carbide-tipped chisels or tempered steel).