硝酸铵
Ammonium nitrate is found as the natural mineral gwihabaite (formerly known as nitrammite) – the ammonium analogue of saltpetre (mineralogial name: niter) – in the driest regions of the Atacama Desert in Chile, often as a crust on the ground or in conjunction with other nitrate, iodate, and halide minerals. Ammonium nitrate was mined there until the Haber–Bosch process made it possible to synthesize nitrates from atmospheric nitrogen, thus rendering nitrate mining obsolete.