Garudapurana 1.158.13

1.158.13

śyāmarūkṣāśmarī cāsya syāccitā kaṇṭakairiva /
pittena dahyate bastiḥ pacyamāna ivoṣṇavān //

The stone from vāta is dusky, rough, and covered as if with thorns; / due to pitta, the bladder burns as though being cooked, accompanied by heat;