Figure 3. A typical IR spectrogram of four rare gallbladder stone types.

A. Phosphate stone: 1036, 605, 564 were the characteristic absorption peaks of phosphate. B. Calcium stearate stone: 2917, 2849, 1575, 1540, 1470, 1112, and 721 cm⁻¹ were the characteristic absorption peaks of calcium stearate. C. protein stone: 1756, 1661, 1575, 1541, 1370, and 1039 cm⁻¹ were the absorption peaks of protein. D. cystine stone: 1622, 1566, 1490, 1409, 847, and 541 cm⁻¹ were the absorption peaks of cystine.