Hello dear, Slate pencils contain calcium carbonate which if taken in excessive amount can cause stone formation in kidneys. The continuous craving for eating inedible substances (like chalk, slate pencils) is known as Pica. It is one of the features of Iron deficiency anemia. Investigations like complete blood count & peripheral blood smear will be helpful in clinching the diagnosis. Based on the reports, management will include administration of supplemental Iron & Folic acid preparations. There can be associated factors like hookworm infection which needs to be managed with Albendazole preparations. Also he needs to take a healthy balanced diet rich in green leafy vegetables. So, kindly consult your General Physician for proper clinical evaluation. Wishing him good health. Take care.