What is a white crystalline substance, C3H7NSO2, containing sulphur, occuring as a constituent of certain rare urinary calculi, and occasionally found as a sediment in urine called?

cystine — A white crystalline substance, C3H7NSO2, containing sulphur, occuring as a constituent of certain rare urinary calculi, and occasionally found as a sediment in urine. (Webster's 1913.)

Sources