In 1684, Anton Von Hyden first described the structure of urinary calculi. The most common types of stones in most of the industrialized countries in present times are composed of calcium oxalate and calcium phosphate. A slight regional variation occurs in the relative proportion of calcium oxalate and calcium phosphate stones, however. In Britain, the mixed type of stone is more common, while in the United States, pure oxalate stones are more frequently found. Racial variations are also considered to affect the geographical distribution of the disease. In regard to sex variations, adult males are more prone to present with kidney stones than are females.