 Ammonium nitrate is not, in the form it is commonly sold, an explosive, but it readily forms explosive mixtures with varying properties when combined with primary explosives such as azides or with fuels such as aluminium powder or fuel oil.ANFO is a mixture of 94% ammonium nitrate ("AN") and 6% fuel oil ("FO") widely used as a bulk industrial explosive.It is used in coal mining, quarrying, metal mining, and civil construction in undemanding applications where the advantages of ANFO's low cost and ease of use matter more than the benefits offered by conventional industrial explosives, such as water resistance, oxygen balance, high detonation velocity, and performance in small diameters.