Some of the substances in urine (uric acid and calcium) may crystallize
and form
kidney stones.
Kidney stones may be as small as a grain of sand
and may be smooth, round, jagged, spiky or asymmetrical. Most stones are yellow to brown in color, but variations in chemical composition can produce stones that are tan, gold or black. The smallest, smoothest stones may pass out of the body with little resistance and minimal discomfort. It is best to dIscuss this with your doctor.