Calcium oxalate

Calcium oxalate is a chemical compound. It is the calcium salt of oxalic acid. It has the chemical formula  or . It can be found as a dry form, or one of several hydrates.

Calcium oxalate can be found as both a mineral and in living things. Plants can make calcium oxalate out of extra calcium from the soil. In humans, it is the most common chemical in kidney stones.

 Occurrence 
Calcium oxalate is most commonly found as the monohydrate, . As a mineral, this is called whewellite. There are also dihydrate () and trihydrate () forms.

Calcium oxalate occurs naturally in many plants as a way of storing extra calcium. In some species, like pineapples, it forms sharp crystals called raphides. Along with the enzyme bromelain, these crystals may help protect the plants from herbivores. Calcium oxalate is the most common oxalate found in lichens.

Calcium oxalate is oxidised into calcium carbonate by living things, especially bacteria.

 Human health 
Having too much oxalate in the body is called hyperoxaluria, and can lead to a kidney failure called oxalosis.

Oxalate is absorbed by water during cooking, with boiling being the most effective.

Calcium oxalate in urine can crystallise into kidney stones. Calcium oxalate is a metabolite of ethylene glycol and is involved in ethylene glycol poisoning.

 Sources 

Category:Calcium salts
Category:Carboxylate salts
Category:Calcium compounds