Lightweight composite or "mineral foam" composite materials can be made from reactive materials such as metal oxides. The materials can be prepared from a reaction of metal oxide(s), phosphate(s) and residual materials to which may be added a reactive foaming agent and/or latex polymer to provide enhanced physical properties. The composite materials can have a density of between about 0.35 to 2.25 g/cc, and may be used for many applications including pre-cast structures, in-situ structures, insulating blocks, slabs and composite wall sections, light weight spheres, mixes and coatings.