Permineralization happens when pore spaces in a fossil are filled with minerals, usually silica, and harden in place. Most petrified wood and many dinosaur bones are preserved in this way. In this lab we are going to take a piece of sponge with lots of holes, sort of like a dinosaur bone, and soak it in sodium silicate. The sodium silicate fills the pores of the sponge and hardens, in much the same way that minerals fill the pores in wood and bone and solidify. Voila! Permineralization in 24 hours.