Silica gel is a
granular,
vitreous,
porous form of
silicon dioxide made synthetically from
sodium silicate. Silica gel is tough and hard; it is more solid than common household
gels like
gelatin or
agar. It is a naturally occurring mineral that is purified and processed into either granular or beaded form. As a
desiccant, it has an average pore size of 2.4 nanometers and has a strong affinity for water molecules.