Calcium oxalate crystal

Calcium oxalate crystal is a mineral composed of calcium cations and oxalate anions, with the basic formula CaC₂O₄, often forming as monohydrate (COM; whewellite), dihydrate (COD; weddellite), or trihydrate (caoxite)[5][7][1]. It forms the major mineral component (∼76%) of human kidney stones and can also be found as a controlled biomineral in plants, where it plays roles in calcium storage and defense[4][8]. In pathology, crystals precipitate when urine or tissue fluid reaches supersaturation, causing stone formation or tissue deposition. In plants, specialized cells tightly regulate the morphology and localization of crystals. Therapies for stone prevention frequently target either the physicochemical environment to prevent precipitation or use agents that modify crystal growth and aggregation[2][6].

Other names

Calcium oxalate (CaOx)calcium oxalate monohydrate (COM)calcium oxalate dihydrate (COD)whewellite (for COM)weddellite (for COD)caoxite (for trihydrate)

Drugs such as citrate increase calcium solubility or inhibit crystal aggregation/growth[2]; polyphosphates prevent nucleation or embed in the crystal lattice to disrupt further growth[2]; thiazides reduce urinary calcium excretion, lessening supersaturation.