<unk>  is a chemical compound that forms needle-shaped crystals. Large quantities are found in the poisonous plant dumb cane. It is also found in rhubarb leaves, various species of Oxalis, and agaves, and (in lower amounts) in spinach.<unk>  crystals in the urine are the most common constituent of human kidney stones, and<unk>  crystal formation is also one of the toxic effects of ethylene glycol poisoning.
Even a small dose of<unk>  is enough to cause intense sensations of burning in the mouth and throat, swelling, and choking. In larger doses, however,<unk>  causes severe digestive upset, breathing difficulties and - if enough is consumed - convulsions, coma and death. Recovery from severe<unk>  poisoning is possible, but permanent liver and kidney damage may have occurred.
Nonsoluble<unk>  crystals are found in plant stems, roots, and leaves. The stalk of the Dieffenbachia produces the most severe reactions. These needle-like crystals produce pain and edema when they contact lips, tongue, oral mucosa, conjunctiva, or skin. Oedema primarily is due to direct trauma from the needle-like crystals and, to a lesser extent, by other plant toxins (e.g. bradykinins, enzymes).<unk>  also forms a major component of beerstone, a brownish precipitate that tends to accumulate within vats, barrels and other containers used in the brewing of beer. Beerstone is composed of<unk>  and magnesium salts and various organic compounds left over from the brewing process; it promotes the growth of unwanted microorganisms that can adversely affect or even ruin the flavor of a batch of beer.
Calcium oxalate
Cerium oxalate
Aluminium phosphate
Calcium phosphate
Sodium cellulose phosphate
Hydrotalcite
Kaolinite
Hypophosphorous acid