It is often found when the copper concentration in an outdoor swimming pool is too high.

This phenomenon is called 'Purple Cyanurate', as it discolours the surfaces and the water of the pool to a purple shade.

Joanneumite is a rare natural mineral found in bat guano with formula Cu(C3N3O3H2)2(NH3)2 which is an ammine.

If instead a weak (2%) cold ammonia solution is used, the dark purple compound CuC3N3O3H•2NH3 is formed instead.

[2] A green coloured copper cyanurate containing no extra water or ammonia ligands also exists: Cu3(C3N3O3)2.