Abstract: A compressed building block formed of a pre-mix of fly ash, Class C type, are combined with various aggregates either ground wood and/or chips, having maybe a small amount of Portland cement added thereto, moisturized, and then either molded, extruded or compressed in a press into the configuration of a block. A plasticizer, wetting agent and surfactant solution may be added to the composition. Boron as a mold retardant and an insecticide, may be added to the composition, to provide the formed block with further beneficial attributes. The blocks may be formed by a system for extruding such blocks from the formulation, or they may be formed by means of a mold or hydraulic or other press and pressed into the configuration of the desired block, needed for the construction.