Improved methods for the production of lightweight, rigid, insulative perlite/cement solid articles such as bricks (62) are provided wherein expanded perlite is first treated with a cement binder followed by application of cement with subsequent mixing and forming. In preferred forms, a continuous belt (12) is provided with laterally spaced apart stations (22-28) for application of perlite, binder, water and Portland cement, respectively, onto the belt (12); these materials are then mixed in a drum mixer (38) to produce a mixture (61) which is poured into a frame assembly (44) for final curing/hardening.