Ammonium oxalate

Ammonium oxalate is a chemical compound with the chemical formula [NH4]2C2O4. Its formula is often written as (NH4)2C2O4 or (COONH4)2. It is an ammonium salt of oxalic acid. It consists of ammonium cations ([NH4]+) and oxalate anions (C2O4(2−)). The structure of ammonium oxalate is ([NH4]+)2[C2O4](2−). Ammonium oxalate sometimes comes as a monohydrate ([NH4]2C2O4*H2O). It is a colorless or white salt under standard conditions and is odorless and non-volatile. It occurs in many plants and vegetables.

Vertebrate
It is produced in the body of vertebrates by metabolism of glyoxylic acid or ascorbic acid. It is not metabolized but excreted in the urine. It is a constituent of some types of kidney stone. It is also found in guano.

Mineralogy
Oxammite is a natural mineral form of ammonium oxalate. This mineral is extremely rare. It is an organic mineral derived from guano.

Chemistry
Ammonium oxalate is used as an analytical reagent and general reducing agent. It and other oxalates are used as anticoagulants, to preserve blood outside the body.

Earth sciences
Acid ammonium oxalate (ammonium oxalate acidified to pH 3 with oxalic acid) is commonly employed in soil chemical analysis to extract iron and aluminium from poorly-crystalline minerals (such as ferrihydrite), iron(II)-bearing minerals (such as magnetite) and organic matter.