 For example, it is found in Tenerife, Spain, where the magnetite grains contain a very high amount of titanium and other impurities.The typical composition is 79.2% iron oxide, 14.6% titanium dioxide, 1.6% manganese oxide, 0.8% silica and aluminum oxide, and trace amounts of chromium.It can also be found in the River Dee, in Aberdeenshire, Scotland, containing 85.3% iron oxide, 9.5% titanium dioxide, 1.0% arsenic, and 1.5% silica and aluminum oxide.