A tiny minority of stones are cystine stones, composed of the amino acid cystine which sometimes leaks into the urine to crystalize and form a yellow or light pink colored stone that is radiopaque under X-ray.

有一小部分结石是胱氨酸结石，是胱氨酸渗入尿液后结晶形成黄色或者淡粉色的结石，在X线下是不透光的。