Do you know which part of the country is nicknamed the “Stone Belt”? Find out this and other fascinating facts about these mineral deposits formed by the human body. You may have heard the oft-cited factoid that kidney stones are as painful as childbirth, but do you know what kidney stones are made of or how to prevent them? Here, we’ll look into the strange, surprising and even “shocking” truths about them. 1. More than one type of stone exists There are four major types of kidney stones: calcium stones, struvite stones, uric acid stones and cystine stones. At around 80% of stones, the calcium type is the most common. Struvite stones sometimes occur after repeated urinary tract infections. Uric acid stones form when urine is too acidic. Cystine stones, which are the rarest, form due to a genetic disorder.