X-ray diffraction studies of the composition of gallstones from English and Australian patients.

The crystalline composition of two collections of gallstones from patients in England and Australia have been determined by the x-ray powder diffraction technique. Twelve substances have been identified including a form of cholesterol which hitherto has not been reported. The weighted percentage composition averaged over each collection shows that cholesterol is the major constituent of the Australian stones and cholesterol and cholesterol monohydrate the major constituents of the English calculi. The cholesterol is possibly a decomposition product of the monohydrate. The calcium carbonates-calcite, aragonite, and vaterite-constitute most of the remainder of the calculi. Although their percentage composition is much smaller than that of the cholesterols, they are nevertheless present in a high proportion of stones. Small traces of apatite, whitlockite, sodium chloride, calcium stearate and palmitic acid (or other long-chain compounds having closely related spacings) have been found. Small spheroids scattered throughout some stones appear to be mainly calcium stearate, although the total quantity available is too small and too impure for a definite identification.