Calciumoxalat
Calcium oxalate is an inorganic salt with the formula CaC2O4. It occurs in two common hydrates: the dihydrate CaC2O4·2H2O (weddellite) and the monohydrate CaC2O4·H2O (whewellite). In nature it forms crystals in many plants (often as needle-like raphides) and can be a metabolic byproduct excreted in urine in humans.
Calcium oxalate is highly insoluble in water and only slightly soluble in acids. It can precipitate from
Biochemically, oxalate is produced endogenously and also obtained from the diet. Dietary calcium can bind oxalate
In plants, calcium oxalate crystals can contribute to tissue rigidity and serve as a defense against herbivores.