An air-droppable wildfire retardant composition including Lassenite N pozzolan is a natural siliceous (amorphous) mineral, consisting of the layers of diatoms and volcanic tuffs of Northern California's Cascade Range. The Lassenite pozzolan is mixed with a thickener such as Bentonite clay, a measured volume of water forming a slurr-type mixture capable of suspending the particles of pozzolan in a mixture having a viscosity sufficient to avoid solids separation. The inventive fire retardant contains substantially three innocuous ingredients which have no harmful effects to the atmosphere, plant, or animal life.