Dimension stone used in homes falls into broad geological groups. Limestone and travertine are sedimentary — formed from compressed sediments, often with visible fossils or pores. Slate is metamorphic — clay-rich rock altered by heat and pressure into thin, splittable layers.
Granite and many hard countertop stones are igneous — cooled from molten rock, generally denser and harder than marble or limestone.
What geology means at home
Softer, more porous stones absorb liquid more readily and may need sealing in wet areas. Harder stones resist scratching but are not automatically stain-proof.
Finish matters as much as geology: a honed travertine floor behaves differently from polished marble on a bathroom wall. Read absorption and hardness for your specific product, not only the category name on the label.