Calcium oxalate crystals are formed in the kidney and urinary tract. When there is a build up of calcium oxalate in the kidneys and urine, stones can form. The kidneys are two bean-shaped organs, each about the size of a fist. They are located just below the rib cage, one on each side of the spine behind the liver, stomach, pancreas and intestines. Healthy kidneys clean waste from the blood and remove it in the urine.
