what is chicken grit made of
Grit generally comes in three types â insoluble, soluble and mixed. 1  Insoluble/Flint Grit â this grit is made of finely crushed granite. When buying Insoluble grit, check with the pet store staff that it is the right size for your flockâs age. 2  Soluble/Shell Grit â ground up oyster shells/cockle shells and or limestone.