Which type of rock do you think would contain the most pore space: limestone, sandstone or shale?

Of these three rock types, shale has the highest amount of pore space (porosity), but the lowest permeability (ability for water to move through the pores).





Shale is made of clay sized particles which are very small, so the pores in the rock are very small also. The small pores resist movement of water through them because of friction between the water and the clay grains. However, the shale has more pore space because the clay particles are flat flakes which can be all jumbled to make more empty space in the rock and because the flakes have small electrostatic charges which tend to repel them from each other.Which type of rock do you think would contain the most pore space: limestone, sandstone or shale?
Sandstone usually has the highest porosity (pore space), followed by limestone, and shale has the least