Oxalic acid forms fine colourless crystals, readily soluble in water, with light nitrogen oxides-like odour. Oxalic acid is used for the extraction of rare metals, polishing of marbles and other stone surfaces, cleaning and polishing of metals, auxiliary textile agents production, for the production of antibiotics (tetracycline etc. ), for the production of oxalates, esters and glyoxalic acid, in the leather industry, in the building industry etc.