The term allotropy has also been applied to inorganic compounds, identical in composition, but assuming different crystallographic forms. Mercuric oxide, sulphide and iodide; arsenic trioxide; titanium dioxide and silicon dioxide may be cited as examples.
It may be recognized by the violet coloration it gives when added to a very dilute solution of potassium bichromate in the presence of hydrochloric acid; by the orange-red colour it gives with a solution of titanium dioxide in concentrated sulphuric acid; and by the precipitate of Prussian blue formed when it is added to a solution containing ferric chloride and potassium ferricyanide.
Titanium Titanium metal made by electrolysis of titanium dioxide in molten calcium chloride.
The hi-tech paving slabs have a top layer containing titanium dioxide which helps to break down pollutant nitrogen dioxide gas from car fumes.
The mineral sands deposits contain ilmenite, a major source of titanium dioxide (TiO2) which is used to produce white pigment.
