Chronic Laxative abuse can result in the formation of which type of stone:
Ref. API Textbook of Medicine. Pg. 784
 
Urinary stones due to chronic laxative abuse is due to gastrointestinal loss of fluid and electrolytes leads to chronic depletion of urinary volume ,relative super saturation and many other pathophysiologic derangements .
These calculi are generally radiolucent with uric acid and ammonium urate as major componenent.
Xanthine
Cysteine
Ammonium urate
Struvite